NLTK-M.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# NLTK"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import nltk\n",
    "import networkx as nx\n",
    "import re\n",
    "from nltk.tag import UnigramTagger\n",
    "from nltk.tag import BigramTagger"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "with open('Data_Sample.txt', 'r', encoding=\"utf8\") as myfile:\n",
    "    data=myfile.read().replace('\\n', '')\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "def ie_preprocess(document):\n",
    "    sentences = nltk.sent_tokenize(document)\n",
    "    sentences = [nltk.word_tokenize(sent) for sent in sentences]\n",
    "    sentences = [nltk.pos_tag(sent) for sent in sentences]\n",
    "    return sentences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[[('\\ufeffCHAPTER', 'RB'),\n",
       "  ('2', 'CD'),\n",
       "  ('The', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('program', 'NN'),\n",
       "  (':', ':'),\n",
       "  ('Little', 'JJ'),\n",
       "  ('Crab', 'JJ'),\n",
       "  ('topics', 'NNS'),\n",
       "  (':', ':'),\n",
       "  ('writing', 'VBG'),\n",
       "  ('code', 'NN'),\n",
       "  (':', ':'),\n",
       "  ('movement', 'NN'),\n",
       "  (',', ','),\n",
       "  ('turning', 'VBG'),\n",
       "  (',', ','),\n",
       "  ('reacting', 'VBG'),\n",
       "  ('to', 'TO'),\n",
       "  ('the', 'DT'),\n",
       "  ('screen', 'NN'),\n",
       "  ('edges', 'VBZ'),\n",
       "  ('concepts', 'NNS'),\n",
       "  (':', ':'),\n",
       "  ('source', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  (',', ','),\n",
       "  ('method', 'NN'),\n",
       "  ('call', 'NN'),\n",
       "  (',', ','),\n",
       "  ('parameter', 'NN'),\n",
       "  (',', ','),\n",
       "  ('sequence', 'NN'),\n",
       "  (',', ','),\n",
       "  ('if-statement', 'JJ'),\n",
       "  ('Exercise', 'NN'),\n",
       "  ('2.1', 'CD'),\n",
       "  ('Start', 'NNP'),\n",
       "  ('Greenfoot', 'NNP'),\n",
       "  ('and', 'CC'),\n",
       "  ('open', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('little-crab', 'JJ'),\n",
       "  ('scenario', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('Place', 'NN'),\n",
       "  ('a', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('into', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('world', 'NN'),\n",
       "  ('and', 'CC'),\n",
       "  ('run', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('program', 'NN'),\n",
       "  ('(', '('),\n",
       "  ('click', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('Run', 'NNP'),\n",
       "  ('button', 'NN'),\n",
       "  (')', ')'),\n",
       "  ('.', '.')],\n",
       " [('What', 'WP'),\n",
       "  ('do', 'VBP'),\n",
       "  ('you', 'PRP'),\n",
       "  ('observe', 'VB'),\n",
       "  ('?', '.')],\n",
       " [('(', '('),\n",
       "  ('Remember', 'VB'),\n",
       "  (':', ':'),\n",
       "  ('If', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('icons', 'NNS'),\n",
       "  ('on', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('right', 'JJ'),\n",
       "  ('appear', 'NN'),\n",
       "  ('striped', 'VBD'),\n",
       "  (',', ','),\n",
       "  ('you', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('to', 'TO'),\n",
       "  ('compile', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('project', 'NN'),\n",
       "  ('first', 'RB'),\n",
       "  ('.', '.'),\n",
       "  (')', ')')],\n",
       " [('On', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('right', 'NN'),\n",
       "  (',', ','),\n",
       "  ('you', 'PRP'),\n",
       "  ('see', 'VBP'),\n",
       "  ('the', 'DT'),\n",
       "  ('classes', 'NNS'),\n",
       "  ('in', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  ('scenario', 'NN'),\n",
       "  ('(', '('),\n",
       "  ('Figure', 'NNP'),\n",
       "  ('2.2', 'CD'),\n",
       "  (')', ')'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('notice', 'VBP'),\n",
       "  ('that', 'IN'),\n",
       "  ('there', 'EX'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('the', 'DT'),\n",
       "  ('usual', 'JJ'),\n",
       "  ('Greenfoot', 'NNP'),\n",
       "  ('Actor', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  (',', ','),\n",
       "  ('a', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('called', 'VBN'),\n",
       "  ('Animal', 'NNP'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('the', 'DT'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('hierarchy', 'NN'),\n",
       "  ('(', '('),\n",
       "  ('denoted', 'VBN'),\n",
       "  ('by', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('arrows', 'NNS'),\n",
       "  (')', ')'),\n",
       "  ('indicates', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('is-a', 'JJ'),\n",
       "  ('relationship', 'NN'),\n",
       "  ('(', '('),\n",
       "  ('also', 'RB'),\n",
       "  ('called', 'VBN'),\n",
       "  ('inheritance', 'NN'),\n",
       "  (')', ')'),\n",
       "  (':', ':'),\n",
       "  ('A', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('animal', 'NN'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('an', 'DT'),\n",
       "  ('animal', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('actor', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('(', '('),\n",
       "  ('It', 'PRP'),\n",
       "  ('follows', 'VBZ'),\n",
       "  ('then', 'RB'),\n",
       "  (',', ','),\n",
       "  ('that', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('also', 'RB'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('actor', 'NN'),\n",
       "  ('.', '.'),\n",
       "  (')', ')')],\n",
       " [('Initially', 'RB'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('will', 'MD'),\n",
       "  ('work', 'VB'),\n",
       "  ('only', 'RB'),\n",
       "  ('with', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('will', 'MD'),\n",
       "  ('talk', 'VB'),\n",
       "  ('a', 'DT'),\n",
       "  ('little', 'RB'),\n",
       "  ('more', 'RBR'),\n",
       "  ('about', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('Actor', 'NNP'),\n",
       "  ('and', 'CC'),\n",
       "  ('Animal', 'NNP'),\n",
       "  ('classes', 'NNS'),\n",
       "  ('later', 'RB'),\n",
       "  ('on', 'IN'),\n",
       "  ('.', '.')],\n",
       " [('If', 'IN'),\n",
       "  ('you', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('done', 'VBN'),\n",
       "  ('the', 'DT'),\n",
       "  ('exercise', 'NN'),\n",
       "  ('above', 'IN'),\n",
       "  (',', ','),\n",
       "  ('then', 'RB'),\n",
       "  ('you', 'PRP'),\n",
       "  ('know', 'VBP'),\n",
       "  ('the', 'DT'),\n",
       "  ('answer', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('the', 'DT'),\n",
       "  ('question', 'NN'),\n",
       "  ('“What', 'WP'),\n",
       "  ('do', 'VBP'),\n",
       "  ('you', 'PRP'),\n",
       "  ('observe', 'VB'),\n",
       "  ('?', '.'),\n",
       "  ('”', 'VB'),\n",
       "  ('It', 'PRP'),\n",
       "  ('is', 'VBZ'),\n",
       "  (':', ':'),\n",
       "  ('“nothing”', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('2.1', 'CD'),\n",
       "  ('The', 'DT'),\n",
       "  ('Little', 'JJ'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('scenario', 'NN'),\n",
       "  ('|', 'VBZ'),\n",
       "  ('17', 'CD'),\n",
       "  ('Figure', 'NN'),\n",
       "  ('2.1', 'CD'),\n",
       "  ('The', 'DT'),\n",
       "  ('Little', 'JJ'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('scenario', 'NN'),\n",
       "  ('Figure', 'NNP'),\n",
       "  ('2.2', 'CD'),\n",
       "  ('The', 'DT'),\n",
       "  ('Little', 'NNP'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('actor', 'NN'),\n",
       "  ('classes', 'VBZ'),\n",
       "  ('The', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('does', 'VBZ'),\n",
       "  ('not', 'RB'),\n",
       "  ('do', 'VB'),\n",
       "  ('anything', 'NN'),\n",
       "  ('when', 'WRB'),\n",
       "  ('Greenfoot', 'NNP'),\n",
       "  ('runs', 'VBZ'),\n",
       "  ('.', '.')],\n",
       " [('This', 'DT'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('because', 'IN'),\n",
       "  ('there', 'EX'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('no', 'DT'),\n",
       "  ('source', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  ('in', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('definition', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  ('that', 'WDT'),\n",
       "  ('specifies', 'VBZ'),\n",
       "  ('what', 'WP'),\n",
       "  ('the', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('should', 'MD'),\n",
       "  ('do', 'VB'),\n",
       "  ('.', '.')],\n",
       " [('In', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  ('chapter', 'NN'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('shall', 'MD'),\n",
       "  ('work', 'VB'),\n",
       "  ('on', 'IN'),\n",
       "  ('changing', 'VBG'),\n",
       "  ('this', 'DT'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('thing', 'NN'),\n",
       "  ('we', 'PRP'),\n",
       "  ('shall', 'MD'),\n",
       "  ('do', 'VB'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('to', 'TO'),\n",
       "  ('make', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('move', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('2.2', 'CD'),\n",
       "  ('Making', 'VBG'),\n",
       "  ('the', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('move', 'NN'),\n",
       "  ('Let', 'NNP'),\n",
       "  ('us', 'PRP'),\n",
       "  ('have', 'VB'),\n",
       "  ('a', 'DT'),\n",
       "  ('look', 'NN'),\n",
       "  ('at', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('source', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('class', 'NN'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('.', '.')],\n",
       " [('Open', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('editor', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('display', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('source', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('(', '('),\n",
       "  ('You', 'PRP'),\n",
       "  ('can', 'MD'),\n",
       "  ('do', 'VB'),\n",
       "  ('this', 'DT'),\n",
       "  ('by', 'IN'),\n",
       "  ('selecting', 'VBG'),\n",
       "  ('the', 'DT'),\n",
       "  ('Open', 'NNP'),\n",
       "  ('editor', 'NN'),\n",
       "  ('function', 'NN'),\n",
       "  ('from', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('class’s', 'NN'),\n",
       "  ('popup', 'NN'),\n",
       "  ('menu', 'NN'),\n",
       "  (',', ','),\n",
       "  ('or', 'CC'),\n",
       "  ('you', 'PRP'),\n",
       "  ('can', 'MD'),\n",
       "  ('just', 'RB'),\n",
       "  ('double-click', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('.', '.'),\n",
       "  (')', ')')],\n",
       " [('The', 'DT'),\n",
       "  ('source', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  ('you', 'PRP'),\n",
       "  ('see', 'VBP'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('shown', 'VBN'),\n",
       "  ('in', 'IN'),\n",
       "  ('Code', 'NNP'),\n",
       "  ('2.1', 'CD'),\n",
       "  ('.', '.')],\n",
       " [('18', 'CD'),\n",
       "  ('|', 'JJ'),\n",
       "  ('Chapter', 'NN'),\n",
       "  ('2', 'CD'),\n",
       "  ('■', 'IN'),\n",
       "  ('The', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('program', 'NN'),\n",
       "  (':', ':'),\n",
       "  ('Little', 'JJ'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('Code', 'NNP'),\n",
       "  ('2.1', 'CD'),\n",
       "  ('The', 'DT'),\n",
       "  ('original', 'JJ'),\n",
       "  ('version', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  ('import', 'NN'),\n",
       "  ('greenfoot', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('*', 'NN'),\n",
       "  (';', ':'),\n",
       "  ('//', 'NNP'),\n",
       "  ('(', '('),\n",
       "  ('World', 'NNP'),\n",
       "  (',', ','),\n",
       "  ('Actor', 'NNP'),\n",
       "  (',', ','),\n",
       "  ('GreenfootImage', 'NNP'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('Greenfoot', 'NNP'),\n",
       "  (')', ')'),\n",
       "  ('/**', 'VBP'),\n",
       "  ('*', '$'),\n",
       "  ('This', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('defines', 'VBZ'),\n",
       "  ('a', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('Crabs', 'NNP'),\n",
       "  ('live', 'VBP'),\n",
       "  ('on', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('beach', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('*/', 'JJ'),\n",
       "  ('public', 'JJ'),\n",
       "  ('class', 'NN'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('extends', 'VBZ'),\n",
       "  ('Animal', 'NNP'),\n",
       "  ('{', '('),\n",
       "  ('public', 'JJ'),\n",
       "  ('void', 'NN'),\n",
       "  ('act', 'NN'),\n",
       "  ('(', '('),\n",
       "  (')', ')'),\n",
       "  ('{', '('),\n",
       "  ('//', 'JJ'),\n",
       "  ('Add', 'NNP'),\n",
       "  ('your', 'PRP$'),\n",
       "  ('action', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  ('here.', 'NN'),\n",
       "  ('}', ')')],\n",
       " [('}', ')'),\n",
       "  ('This', 'DT'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('a', 'DT'),\n",
       "  ('standard', 'JJ'),\n",
       "  ('Java', 'NNP'),\n",
       "  ('class', 'NN'),\n",
       "  ('definition', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('That', 'DT'),\n",
       "  ('is', 'VBZ'),\n",
       "  (',', ','),\n",
       "  ('this', 'DT'),\n",
       "  ('text', 'NN'),\n",
       "  ('defines', 'VBZ'),\n",
       "  ('what', 'WP'),\n",
       "  ('the', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('can', 'MD'),\n",
       "  ('do', 'VB'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('will', 'MD'),\n",
       "  ('look', 'VB'),\n",
       "  ('at', 'IN'),\n",
       "  ('it', 'PRP'),\n",
       "  ('in', 'IN'),\n",
       "  ('detail', 'NN'),\n",
       "  ('a', 'DT'),\n",
       "  ('little', 'JJ'),\n",
       "  ('later', 'RB'),\n",
       "  ('.', '.')],\n",
       " [('For', 'IN'),\n",
       "  ('now', 'RB'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('will', 'MD'),\n",
       "  ('concentrate', 'VB'),\n",
       "  ('on', 'IN'),\n",
       "  ('getting', 'VBG'),\n",
       "  ('the', 'DT'),\n",
       "  ('crab', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('move', 'VB'),\n",
       "  ('.', '.')],\n",
       " [('Within', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('definition', 'NN'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('can', 'MD'),\n",
       "  ('see', 'VB'),\n",
       "  ('what', 'WP'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('called', 'VBN'),\n",
       "  ('the', 'DT'),\n",
       "  ('act', 'NN'),\n",
       "  ('method', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('It', 'PRP'),\n",
       "  ('looks', 'VBZ'),\n",
       "  ('like', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  (':', ':'),\n",
       "  ('public', 'JJ'),\n",
       "  ('void', 'NN'),\n",
       "  ('act', 'NN'),\n",
       "  ('(', '('),\n",
       "  (')', ')'),\n",
       "  ('{', '('),\n",
       "  ('//', 'JJ'),\n",
       "  ('Add', 'NNP'),\n",
       "  ('your', 'PRP$'),\n",
       "  ('action', 'NN'),\n",
       "  ('code', 'NN'),\n",
       "  ('here.', 'NN'),\n",
       "  ('}', ')')],\n",
       " [('The', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('line', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('the', 'DT'),\n",
       "  ('signature', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('method', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('last', 'JJ'),\n",
       "  ('three', 'CD'),\n",
       "  ('lines—the', 'VBD'),\n",
       "  ('two', 'CD'),\n",
       "  ('curly', 'JJ'),\n",
       "  ('brackets', 'NNS'),\n",
       "  ('and', 'CC'),\n",
       "  ('anything', 'NN'),\n",
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       "  ('bracket', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('use', 'VBP'),\n",
       "  ('four', 'CD'),\n",
       "  ('spaces', 'NNS'),\n",
       "  ('for', 'IN'),\n",
       "  ('one', 'CD'),\n",
       "  ('level', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('indentation', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('Tab', 'NNP'),\n",
       "  ('key', 'NN'),\n",
       "  ('will', 'MD'),\n",
       "  ('insert', 'VB'),\n",
       "  ('spaces', 'NNS'),\n",
       "  ('in', 'IN'),\n",
       "  ('your', 'PRP$'),\n",
       "  ('editor', 'NN'),\n",
       "  ('for', 'IN'),\n",
       "  ('one', 'CD'),\n",
       "  ('level', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('indentation', 'NN'),\n",
       "  ('as', 'IN'),\n",
       "  ('well', 'RB'),\n",
       "  ('.', '.')],\n",
       " [('Taking', 'VBG'),\n",
       "  ('care', 'NN'),\n",
       "  ('with', 'IN'),\n",
       "  ('indentation', 'NN'),\n",
       "  ('in', 'IN'),\n",
       "  ('your', 'PRP$'),\n",
       "  ('own', 'JJ'),\n",
       "  ('code', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('very', 'RB'),\n",
       "  ('important', 'JJ'),\n",
       "  ('.', '.')],\n",
       " [('If', 'IN'),\n",
       "  ('you', 'PRP'),\n",
       "  ('do', 'VBP'),\n",
       "  ('not', 'RB'),\n",
       "  ('indent', 'VB'),\n",
       "  ('carefully', 'RB'),\n",
       "  (',', ','),\n",
       "  ('some', 'DT'),\n",
       "  ('errors', 'NNS'),\n",
       "  ('(', '('),\n",
       "  ('particularly', 'RB'),\n",
       "  ('misplaced', 'VBN'),\n",
       "  ('or', 'CC'),\n",
       "  ('mismatched', 'VBN'),\n",
       "  ('curly', 'JJ'),\n",
       "  ('brackets', 'NNS'),\n",
       "  (')', ')'),\n",
       "  ('are', 'VBP'),\n",
       "  ('very', 'RB'),\n",
       "  ('hard', 'JJ'),\n",
       "  ('to', 'TO'),\n",
       "  ('spot', 'VB'),\n",
       "  ('.', '.')],\n",
       " [('Proper', 'JJ'),\n",
       "  ('indentation', 'NN'),\n",
       "  ('makes', 'VBZ'),\n",
       "  ('code', 'RB'),\n",
       "  ('much', 'JJ'),\n",
       "  ('easier', 'JJR'),\n",
       "  ('to', 'TO'),\n",
       "  ('read', 'VB'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('thus', 'RB'),\n",
       "  ('avoid', 'VB'),\n",
       "  ('potential', 'JJ'),\n",
       "  ('errors', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('2.5', 'CD'),\n",
       "  ('Summary', 'NNP'),\n",
       "  ('of', 'IN'),\n",
       "  ('programming', 'VBG'),\n",
       "  ('techniques', 'NNS'),\n",
       "  ('In', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  ('book', 'NN'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('are', 'VBP'),\n",
       "  ('discussing', 'VBG'),\n",
       "  ('programming', 'VBG'),\n",
       "  ('from', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('very', 'RB'),\n",
       "  ('example-driven', 'JJ'),\n",
       "  ('perspective', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('introduce', 'VBP'),\n",
       "  ('general', 'JJ'),\n",
       "  ('programming', 'NN'),\n",
       "  ('techniques', 'NNS'),\n",
       "  ('as', 'IN'),\n",
       "  ('we', 'PRP'),\n",
       "  ('need', 'VBP'),\n",
       "  ('them', 'PRP'),\n",
       "  ('to', 'TO'),\n",
       "  ('improve', 'VB'),\n",
       "  ('our', 'PRP$'),\n",
       "  ('scenarios', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('shall', 'MD'),\n",
       "  ('summarize', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('important', 'JJ'),\n",
       "  ('programming', 'NN'),\n",
       "  ('techniques', 'NNS'),\n",
       "  ('at', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('end', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('each', 'DT'),\n",
       "  ('chapter', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('make', 'VB'),\n",
       "  ('it', 'PRP'),\n",
       "  ('clear', 'JJ'),\n",
       "  ('what', 'WP'),\n",
       "  ('you', 'PRP'),\n",
       "  ('really', 'RB'),\n",
       "  ('need', 'VB'),\n",
       "  ('to', 'TO'),\n",
       "  ('take', 'VB'),\n",
       "  ('away', 'RP'),\n",
       "  ('from', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('discussion', 'NN'),\n",
       "  ('in', 'IN'),\n",
       "  ('order', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('progress', 'VB'),\n",
       "  ('well', 'RB'),\n",
       "  ('.', '.')],\n",
       " [('In', 'IN'),\n",
       "  ('this', 'DT'),\n",
       "  ('chapter', 'NN'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('seen', 'VBN'),\n",
       "  ('how', 'WRB'),\n",
       "  ('to', 'TO'),\n",
       "  ('call', 'VB'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('(', '('),\n",
       "  ('such', 'JJ'),\n",
       "  ('as', 'IN'),\n",
       "  ('move', 'NN'),\n",
       "  ('(', '('),\n",
       "  (')', ')'),\n",
       "  (')', ')'),\n",
       "  (',', ','),\n",
       "  ('with', 'IN'),\n",
       "  ('and', 'CC'),\n",
       "  ('without', 'IN'),\n",
       "  ('parameters', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('This', 'DT'),\n",
       "  ('will', 'MD'),\n",
       "  ('form', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('basis', 'NN'),\n",
       "  ('for', 'IN'),\n",
       "  ('all', 'DT'),\n",
       "  ('further', 'JJ'),\n",
       "  ('Java', 'NNP'),\n",
       "  ('programming', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('also', 'RB'),\n",
       "  ('learnt', 'VBN'),\n",
       "  ('to', 'TO'),\n",
       "  ('identify', 'VB'),\n",
       "  ('the', 'DT'),\n",
       "  ('body', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('act', 'NN'),\n",
       "  ('method—this', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('where', 'WRB'),\n",
       "  ('we', 'PRP'),\n",
       "  ('start', 'VBP'),\n",
       "  ('writing', 'VBG'),\n",
       "  ('our', 'PRP$'),\n",
       "  ('instructions', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('You', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('encountered', 'VBN'),\n",
       "  ('some', 'DT'),\n",
       "  ('error', 'NN'),\n",
       "  ('messages', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('This', 'DT'),\n",
       "  ('will', 'MD'),\n",
       "  ('continue', 'VB'),\n",
       "  ('throughout', 'IN'),\n",
       "  ('all', 'DT'),\n",
       "  ('your', 'PRP$'),\n",
       "  ('programming', 'NN'),\n",
       "  ('endeavors', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('all', 'DT'),\n",
       "  ('make', 'VBP'),\n",
       "  ('mistakes', 'NNS'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('we', 'PRP'),\n",
       "  ('all', 'DT'),\n",
       "  ('encounter', 'VBP'),\n",
       "  ('error', 'NN'),\n",
       "  ('messages', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('This', 'DT'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('not', 'RB'),\n",
       "  ('a', 'DT'),\n",
       "  ('sign', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('bad', 'JJ'),\n",
       "  ('programmer—it', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('a', 'DT'),\n",
       "  ('normal', 'JJ'),\n",
       "  ('part', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('programming', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('We', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('encountered', 'VBN'),\n",
       "  ('a', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('glimpse', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('inheritance', 'NN'),\n",
       "  (':', ':'),\n",
       "  ('Classes', 'NNS'),\n",
       "  ('inherit', 'VBP'),\n",
       "  ('the', 'DT'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('from', 'IN'),\n",
       "  ('their', 'PRP$'),\n",
       "  ('superclasses', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('Documentation', 'NNP'),\n",
       "  ('view', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('gives', 'VBZ'),\n",
       "  ('us', 'PRP'),\n",
       "  ('a', 'DT'),\n",
       "  ('summary', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('available', 'JJ'),\n",
       "  ('.', '.')],\n",
       " [('And', 'CC'),\n",
       "  (',', ','),\n",
       "  ('very', 'RB'),\n",
       "  ('importantly', 'RB'),\n",
       "  (',', ','),\n",
       "  ('we', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('seen', 'VBN'),\n",
       "  ('how', 'WRB'),\n",
       "  ('to', 'TO'),\n",
       "  ('make', 'VB'),\n",
       "  ('decisions', 'NNS'),\n",
       "  (':', ':'),\n",
       "  ('We', 'PRP'),\n",
       "  ('have', 'VBP'),\n",
       "  ('used', 'VBN'),\n",
       "  ('an', 'DT'),\n",
       "  ('if-statement', 'JJ'),\n",
       "  ('for', 'IN'),\n",
       "  ('conditional', 'JJ'),\n",
       "  ('execution', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('This', 'DT'),\n",
       "  ('went', 'VBD'),\n",
       "  ('hand', 'NN'),\n",
       "  ('in', 'IN'),\n",
       "  ('hand', 'NN'),\n",
       "  ('with', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('appearance', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('type', 'NN'),\n",
       "  ('boolean', 'NN'),\n",
       "  (',', ','),\n",
       "  ('a', 'DT'),\n",
       "  ('value', 'NN'),\n",
       "  ('that', 'WDT'),\n",
       "  ('can', 'MD'),\n",
       "  ('be', 'VB'),\n",
       "  ('true', 'JJ'),\n",
       "  ('or', 'CC'),\n",
       "  ('false', 'JJ'),\n",
       "  ('.', '.')],\n",
       " [('26', 'CD'),\n",
       "  ('|', 'JJ'),\n",
       "  ('Chapter', 'NN'),\n",
       "  ('2', 'CD'),\n",
       "  ('■', 'IN'),\n",
       "  ('The', 'DT'),\n",
       "  ('first', 'JJ'),\n",
       "  ('program', 'NN'),\n",
       "  (':', ':'),\n",
       "  ('Little', 'JJ'),\n",
       "  ('Crab', 'NNP'),\n",
       "  ('Concept', 'NNP'),\n",
       "  ('summary', 'JJ'),\n",
       "  ('■', 'VBD'),\n",
       "  ('A', 'DT'),\n",
       "  ('method', 'NN'),\n",
       "  ('call', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('instruction', 'NN'),\n",
       "  ('that', 'WDT'),\n",
       "  ('tells', 'VBZ'),\n",
       "  ('an', 'DT'),\n",
       "  ('object', 'NN'),\n",
       "  ('to', 'TO'),\n",
       "  ('perform', 'VB'),\n",
       "  ('an', 'DT'),\n",
       "  ('action', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('action', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('defined', 'VBN'),\n",
       "  ('by', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('method', 'NN'),\n",
       "  ('of', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('object', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('■', 'JJ'),\n",
       "  ('Additional', 'NNP'),\n",
       "  ('information', 'NN'),\n",
       "  ('can', 'MD'),\n",
       "  ('be', 'VB'),\n",
       "  ('passed', 'VBN'),\n",
       "  ('to', 'TO'),\n",
       "  ('some', 'DT'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('within', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('parentheses', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('The', 'DT'),\n",
       "  ('value', 'NN'),\n",
       "  ('passed', 'VBN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('called', 'VBN'),\n",
       "  ('a', 'DT'),\n",
       "  ('parameter', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('■', 'JJ'),\n",
       "  ('Multiple', 'NNP'),\n",
       "  ('instructions', 'NNS'),\n",
       "  ('are', 'VBP'),\n",
       "  ('executed', 'VBN'),\n",
       "  ('in', 'IN'),\n",
       "  ('sequence', 'NN'),\n",
       "  (',', ','),\n",
       "  ('one', 'CD'),\n",
       "  ('after', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('other', 'JJ'),\n",
       "  (',', ','),\n",
       "  ('in', 'IN'),\n",
       "  ('the', 'DT'),\n",
       "  ('order', 'NN'),\n",
       "  ('in', 'IN'),\n",
       "  ('which', 'WDT'),\n",
       "  ('they', 'PRP'),\n",
       "  ('are', 'VBP'),\n",
       "  ('written', 'VBN'),\n",
       "  ('.', '.')],\n",
       " [('■', 'NN'),\n",
       "  ('When', 'WRB'),\n",
       "  ('a', 'DT'),\n",
       "  ('class', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('compiled', 'VBN'),\n",
       "  (',', ','),\n",
       "  ('the', 'DT'),\n",
       "  ('compiler', 'NN'),\n",
       "  ('checks', 'NNS'),\n",
       "  ('to', 'TO'),\n",
       "  ('see', 'VB'),\n",
       "  ('whether', 'IN'),\n",
       "  ('there', 'EX'),\n",
       "  ('are', 'VBP'),\n",
       "  ('any', 'DT'),\n",
       "  ('errors', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('If', 'IN'),\n",
       "  ('an', 'DT'),\n",
       "  ('error', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('found', 'VBN'),\n",
       "  (',', ','),\n",
       "  ('an', 'DT'),\n",
       "  ('error', 'NN'),\n",
       "  ('message', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('displayed', 'VBN'),\n",
       "  ('.', '.')],\n",
       " [('■', 'VB'),\n",
       "  ('A', 'NNP'),\n",
       "  ('subclass', 'NN'),\n",
       "  ('inherits', 'VBZ'),\n",
       "  ('all', 'PDT'),\n",
       "  ('the', 'DT'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('from', 'IN'),\n",
       "  ('its', 'PRP$'),\n",
       "  ('superclass', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('That', 'DT'),\n",
       "  ('means', 'VBZ'),\n",
       "  ('that', 'IN'),\n",
       "  ('it', 'PRP'),\n",
       "  ('has', 'VBZ'),\n",
       "  (',', ','),\n",
       "  ('and', 'CC'),\n",
       "  ('can', 'MD'),\n",
       "  ('use', 'VB'),\n",
       "  (',', ','),\n",
       "  ('all', 'DT'),\n",
       "  ('methods', 'NNS'),\n",
       "  ('that', 'IN'),\n",
       "  ('its', 'PRP$'),\n",
       "  ('superclass', 'NN'),\n",
       "  ('defines', 'NNS'),\n",
       "  ('.', '.')],\n",
       " [('■', 'NN'),\n",
       "  ('Calling', 'VBG'),\n",
       "  ('a', 'DT'),\n",
       "  ('method', 'NN'),\n",
       "  ('with', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('void', 'JJ'),\n",
       "  ('return', 'NN'),\n",
       "  ('type', 'NN'),\n",
       "  ('issues', 'NNS'),\n",
       "  ('a', 'DT'),\n",
       "  ('command', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('Calling', 'VBG'),\n",
       "  ('a', 'DT'),\n",
       "  ('method', 'NN'),\n",
       "  ('with', 'IN'),\n",
       "  ('a', 'DT'),\n",
       "  ('non-void', 'JJ'),\n",
       "  ('return', 'NN'),\n",
       "  ('type', 'NN'),\n",
       "  ('asks', 'VBZ'),\n",
       "  ('a', 'DT'),\n",
       "  ('question', 'NN'),\n",
       "  ('.', '.')],\n",
       " [('■', 'VB'),\n",
       "  ('An', 'DT'),\n",
       "  ('if-statement', 'JJ'),\n",
       "  ('can', 'MD'),\n",
       "  ('be', 'VB'),\n",
       "  ('used', 'VBN'),\n",
       "  ('to', 'TO'),\n",
       "  ('write', 'VB'),\n",
       "  ('instructions', 'NNS'),\n",
       "  ('that', 'WDT'),\n",
       "  ('are', 'VBP'),\n",
       "  ('executed', 'VBN'),\n",
       "  ('only', 'RB'),\n",
       "  ('when', 'WRB'),\n",
       "  ('a', 'DT'),\n",
       "  ('certain', 'JJ'),\n",
       "  ('condition', 'NN'),\n",
       "  ('is', 'VBZ'),\n",
       "  ('true', 'JJ'),\n",
       "  ('.', '.')]]"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sentences = ie_preprocess(data)\n",
    "sentences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(S\n",
      "  ﻿CHAPTER/RB\n",
      "  2/CD\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/JJ\n",
      "  topics/NNS\n",
      "  :/:\n",
      "  writing/VBG\n",
      "  (NP code/NN)\n",
      "  :/:\n",
      "  (NP movement/NN)\n",
      "  ,/,\n",
      "  turning/VBG\n",
      "  ,/,\n",
      "  reacting/VBG\n",
      "  to/TO\n",
      "  (NP the/DT screen/NN)\n",
      "  edges/VBZ\n",
      "  concepts/NNS\n",
      "  :/:\n",
      "  (NP source/NN)\n",
      "  (NP code/NN)\n",
      "  ,/,\n",
      "  (NP method/NN)\n",
      "  (NP call/NN)\n",
      "  ,/,\n",
      "  (NP parameter/NN)\n",
      "  ,/,\n",
      "  (NP sequence/NN)\n",
      "  ,/,\n",
      "  (NP if-statement/JJ Exercise/NN)\n",
      "  2.1/CD\n",
      "  Start/NNP\n",
      "  Greenfoot/NNP\n",
      "  and/CC\n",
      "  open/VB\n",
      "  (NP the/DT little-crab/JJ scenario/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Place/NN)\n",
      "  (NP a/DT crab/NN)\n",
      "  into/IN\n",
      "  (NP the/DT world/NN)\n",
      "  and/CC\n",
      "  run/VB\n",
      "  (NP the/DT program/NN)\n",
      "  (/(\n",
      "  click/VB\n",
      "  the/DT\n",
      "  Run/NNP\n",
      "  (NP button/NN)\n",
      "  )/)\n",
      "  ./.)\n",
      "(S What/WP do/VBP you/PRP observe/VB ?/.)\n",
      "(S\n",
      "  (/(\n",
      "  Remember/VB\n",
      "  :/:\n",
      "  If/IN\n",
      "  (NP the/DT class/NN)\n",
      "  icons/NNS\n",
      "  on/IN\n",
      "  (NP the/DT right/JJ appear/NN)\n",
      "  striped/VBD\n",
      "  ,/,\n",
      "  you/PRP\n",
      "  have/VBP\n",
      "  to/TO\n",
      "  compile/VB\n",
      "  (NP the/DT project/NN)\n",
      "  first/RB\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  On/IN\n",
      "  (NP the/DT right/NN)\n",
      "  ,/,\n",
      "  you/PRP\n",
      "  see/VBP\n",
      "  the/DT\n",
      "  classes/NNS\n",
      "  in/IN\n",
      "  (NP this/DT scenario/NN)\n",
      "  (/(\n",
      "  Figure/NNP\n",
      "  2.2/CD\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  notice/VBP\n",
      "  that/IN\n",
      "  there/EX\n",
      "  is/VBZ\n",
      "  the/DT\n",
      "  usual/JJ\n",
      "  Greenfoot/NNP\n",
      "  Actor/NNP\n",
      "  (NP class/NN)\n",
      "  ,/,\n",
      "  (NP a/DT class/NN)\n",
      "  called/VBN\n",
      "  Animal/NNP\n",
      "  ,/,\n",
      "  and/CC\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT hierarchy/NN)\n",
      "  (/(\n",
      "  denoted/VBN\n",
      "  by/IN\n",
      "  the/DT\n",
      "  arrows/NNS\n",
      "  )/)\n",
      "  indicates/VBZ\n",
      "  (NP an/DT is-a/JJ relationship/NN)\n",
      "  (/(\n",
      "  also/RB\n",
      "  called/VBN\n",
      "  (NP inheritance/NN)\n",
      "  )/)\n",
      "  :/:\n",
      "  (NP A/DT crab/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT animal/NN)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  (NP an/DT animal/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT actor/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  It/PRP\n",
      "  follows/VBZ\n",
      "  then/RB\n",
      "  ,/,\n",
      "  that/IN\n",
      "  (NP a/DT crab/NN)\n",
      "  also/RB\n",
      "  is/VBZ\n",
      "  (NP an/DT actor/NN)\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  Initially/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  will/MD\n",
      "  work/VB\n",
      "  only/RB\n",
      "  with/IN\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  will/MD\n",
      "  talk/VB\n",
      "  a/DT\n",
      "  little/RB\n",
      "  more/RBR\n",
      "  about/IN\n",
      "  the/DT\n",
      "  Actor/NNP\n",
      "  and/CC\n",
      "  Animal/NNP\n",
      "  classes/NNS\n",
      "  later/RB\n",
      "  on/IN\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  you/PRP\n",
      "  have/VBP\n",
      "  done/VBN\n",
      "  (NP the/DT exercise/NN)\n",
      "  above/IN\n",
      "  ,/,\n",
      "  then/RB\n",
      "  you/PRP\n",
      "  know/VBP\n",
      "  (NP the/DT answer/NN)\n",
      "  to/TO\n",
      "  (NP the/DT question/NN)\n",
      "  “What/WP\n",
      "  do/VBP\n",
      "  you/PRP\n",
      "  observe/VB\n",
      "  ?/.\n",
      "  ”/VB\n",
      "  It/PRP\n",
      "  is/VBZ\n",
      "  :/:\n",
      "  (NP “nothing”/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  2.1/CD\n",
      "  The/DT\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  (NP scenario/NN)\n",
      "  |/VBZ\n",
      "  17/CD\n",
      "  (NP Figure/NN)\n",
      "  2.1/CD\n",
      "  The/DT\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  (NP scenario/NN)\n",
      "  Figure/NNP\n",
      "  2.2/CD\n",
      "  The/DT\n",
      "  Little/NNP\n",
      "  Crab/NNP\n",
      "  (NP actor/NN)\n",
      "  classes/VBZ\n",
      "  (NP The/DT crab/NN)\n",
      "  does/VBZ\n",
      "  not/RB\n",
      "  do/VB\n",
      "  (NP anything/NN)\n",
      "  when/WRB\n",
      "  Greenfoot/NNP\n",
      "  runs/VBZ\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  is/VBZ\n",
      "  because/IN\n",
      "  there/EX\n",
      "  is/VBZ\n",
      "  (NP no/DT source/NN)\n",
      "  (NP code/NN)\n",
      "  in/IN\n",
      "  (NP the/DT definition/NN)\n",
      "  of/IN\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  that/WDT\n",
      "  specifies/VBZ\n",
      "  what/WP\n",
      "  (NP the/DT crab/NN)\n",
      "  should/MD\n",
      "  do/VB\n",
      "  ./.)\n",
      "(S\n",
      "  In/IN\n",
      "  (NP this/DT chapter/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  shall/MD\n",
      "  work/VB\n",
      "  on/IN\n",
      "  changing/VBG\n",
      "  this/DT\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT first/JJ thing/NN)\n",
      "  we/PRP\n",
      "  shall/MD\n",
      "  do/VB\n",
      "  is/VBZ\n",
      "  to/TO\n",
      "  make/VB\n",
      "  (NP the/DT crab/NN)\n",
      "  (NP move/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  2.2/CD\n",
      "  Making/VBG\n",
      "  (NP the/DT crab/NN)\n",
      "  (NP move/NN)\n",
      "  Let/NNP\n",
      "  us/PRP\n",
      "  have/VB\n",
      "  (NP a/DT look/NN)\n",
      "  at/IN\n",
      "  (NP the/DT source/NN)\n",
      "  (NP code/NN)\n",
      "  of/IN\n",
      "  (NP class/NN)\n",
      "  Crab/NNP\n",
      "  ./.)\n",
      "(S\n",
      "  Open/VB\n",
      "  (NP the/DT editor/NN)\n",
      "  to/TO\n",
      "  display/VB\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP source/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  You/PRP\n",
      "  can/MD\n",
      "  do/VB\n",
      "  this/DT\n",
      "  by/IN\n",
      "  selecting/VBG\n",
      "  the/DT\n",
      "  Open/NNP\n",
      "  (NP editor/NN)\n",
      "  (NP function/NN)\n",
      "  from/IN\n",
      "  (NP the/DT class’s/NN)\n",
      "  (NP popup/NN)\n",
      "  (NP menu/NN)\n",
      "  ,/,\n",
      "  or/CC\n",
      "  you/PRP\n",
      "  can/MD\n",
      "  just/RB\n",
      "  double-click/VB\n",
      "  (NP the/DT class/NN)\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  (NP The/DT source/NN)\n",
      "  (NP code/NN)\n",
      "  you/PRP\n",
      "  see/VBP\n",
      "  is/VBZ\n",
      "  shown/VBN\n",
      "  in/IN\n",
      "  Code/NNP\n",
      "  2.1/CD\n",
      "  ./.)\n",
      "(S\n",
      "  18/CD\n",
      "  (NP |/JJ Chapter/NN)\n",
      "  2/CD\n",
      "  ■/IN\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  Code/NNP\n",
      "  2.1/CD\n",
      "  (NP The/DT original/JJ version/NN)\n",
      "  of/IN\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  (NP import/NN)\n",
      "  (NP greenfoot/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP */NN)\n",
      "  ;/:\n",
      "  ///NNP\n",
      "  (/(\n",
      "  World/NNP\n",
      "  ,/,\n",
      "  Actor/NNP\n",
      "  ,/,\n",
      "  GreenfootImage/NNP\n",
      "  ,/,\n",
      "  and/CC\n",
      "  Greenfoot/NNP\n",
      "  )/)\n",
      "  /**/VBP\n",
      "  */$\n",
      "  (NP This/DT class/NN)\n",
      "  defines/VBZ\n",
      "  (NP a/DT crab/NN)\n",
      "  ./.)\n",
      "(S Crabs/NNP live/VBP on/IN (NP the/DT beach/NN) ./.)\n",
      "(S\n",
      "  (NP *//JJ public/JJ class/NN)\n",
      "  Crab/NNP\n",
      "  extends/VBZ\n",
      "  Animal/NNP\n",
      "  {/(\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  ///JJ\n",
      "  Add/NNP\n",
      "  your/PRP$\n",
      "  (NP action/NN)\n",
      "  (NP code/NN)\n",
      "  (NP here./NN)\n",
      "  }/))\n",
      "(S\n",
      "  }/)\n",
      "  This/DT\n",
      "  is/VBZ\n",
      "  a/DT\n",
      "  standard/JJ\n",
      "  Java/NNP\n",
      "  (NP class/NN)\n",
      "  (NP definition/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  That/DT\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  (NP this/DT text/NN)\n",
      "  defines/VBZ\n",
      "  what/WP\n",
      "  (NP the/DT crab/NN)\n",
      "  can/MD\n",
      "  do/VB\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  will/MD\n",
      "  look/VB\n",
      "  at/IN\n",
      "  it/PRP\n",
      "  in/IN\n",
      "  (NP detail/NN)\n",
      "  a/DT\n",
      "  little/JJ\n",
      "  later/RB\n",
      "  ./.)\n",
      "(S\n",
      "  For/IN\n",
      "  now/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  will/MD\n",
      "  concentrate/VB\n",
      "  on/IN\n",
      "  getting/VBG\n",
      "  (NP the/DT crab/NN)\n",
      "  to/TO\n",
      "  move/VB\n",
      "  ./.)\n",
      "(S\n",
      "  Within/IN\n",
      "  (NP this/DT class/NN)\n",
      "  (NP definition/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  see/VB\n",
      "  what/WP\n",
      "  is/VBZ\n",
      "  called/VBN\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  It/PRP\n",
      "  looks/VBZ\n",
      "  like/IN\n",
      "  this/DT\n",
      "  :/:\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  ///JJ\n",
      "  Add/NNP\n",
      "  your/PRP$\n",
      "  (NP action/NN)\n",
      "  (NP code/NN)\n",
      "  (NP here./NN)\n",
      "  }/))\n",
      "(S\n",
      "  (NP The/DT first/JJ line/NN)\n",
      "  is/VBZ\n",
      "  (NP the/DT signature/NN)\n",
      "  of/IN\n",
      "  (NP the/DT method/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  The/DT\n",
      "  last/JJ\n",
      "  three/CD\n",
      "  lines—the/VBD\n",
      "  two/CD\n",
      "  curly/JJ\n",
      "  brackets/NNS\n",
      "  and/CC\n",
      "  (NP anything/NN)\n",
      "  between/IN\n",
      "  (NP them—is/NN)\n",
      "  called/VBN\n",
      "  (NP the/DT body/NN)\n",
      "  of/IN\n",
      "  (NP the/DT method/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Here/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  add/VB\n",
      "  (NP some/DT code/NN)\n",
      "  that/IN\n",
      "  determines/VBZ\n",
      "  the/DT\n",
      "  actions/NNS\n",
      "  of/IN\n",
      "  (NP the/DT crab/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  can/MD\n",
      "  replace/VB\n",
      "  (NP the/DT gray/JJ text/NN)\n",
      "  in/IN\n",
      "  (NP the/DT middle/NN)\n",
      "  with/IN\n",
      "  (NP a/DT command/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  One/CD\n",
      "  (NP such/JJ command/NN)\n",
      "  is/VBZ\n",
      "  move/NNP\n",
      "  (/(\n",
      "  )/)\n",
      "  ;/:\n",
      "  Note/CC\n",
      "  that/IN\n",
      "  it/PRP\n",
      "  has/VBZ\n",
      "  to/TO\n",
      "  be/VB\n",
      "  written/VBN\n",
      "  exactly/RB\n",
      "  as/IN\n",
      "  shown/VBN\n",
      "  ,/,\n",
      "  including/VBG\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  and/CC\n",
      "  (NP the/DT semicolon/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  should/MD\n",
      "  then/RB\n",
      "  look/VB\n",
      "  like/IN\n",
      "  this/DT\n",
      "  :/:\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  2.3/CD\n",
      "  Turning/VBG\n",
      "  |/JJ\n",
      "  19/CD\n",
      "  (NP Exercise/NN)\n",
      "  2.2/CD\n",
      "  Change/NNP\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  in/IN\n",
      "  your/PRP$\n",
      "  (NP crab/NN)\n",
      "  (NP class/NN)\n",
      "  to/TO\n",
      "  include/VB\n",
      "  (NP the/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  ,/,\n",
      "  as/IN\n",
      "  shown/VBN\n",
      "  above/IN\n",
      "  ./.)\n",
      "(S\n",
      "  Compile/IN\n",
      "  (NP the/DT scenario/NN)\n",
      "  (/(\n",
      "  by/IN\n",
      "  clicking/VBG\n",
      "  the/DT\n",
      "  Compile/NNP\n",
      "  All/NNP\n",
      "  (NP button/NN)\n",
      "  )/)\n",
      "  and/CC\n",
      "  (NP place/NN)\n",
      "  (NP a/DT crab/NN)\n",
      "  into/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ./.)\n",
      "(S Try/VB clicking/VBG the/DT Act/NNP and/CC Run/NNP buttons/NNS ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.3/CD\n",
      "  (NP Place/NN)\n",
      "  (NP multiple/JJ crabs/NN)\n",
      "  into/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ./.)\n",
      "(S Run/VB (NP the/DT scenario/NN) ./.)\n",
      "(S What/WP do/VBP you/PRP observe/VB ?/.)\n",
      "(S\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  (NP A/DT method/NN)\n",
      "  (NP call/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT instruction/NN)\n",
      "  that/WDT\n",
      "  tells/VBZ\n",
      "  (NP an/DT object/NN)\n",
      "  to/TO\n",
      "  perform/VB\n",
      "  (NP an/DT action/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT action/NN)\n",
      "  is/VBZ\n",
      "  defined/VBN\n",
      "  by/IN\n",
      "  (NP a/DT method/NN)\n",
      "  of/IN\n",
      "  (NP the/DT object/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  You/PRP\n",
      "  will/MD\n",
      "  see/VB\n",
      "  that/IN\n",
      "  (NP the/DT crab/NN)\n",
      "  can/MD\n",
      "  now/RB\n",
      "  move/VB\n",
      "  across/IN\n",
      "  (NP the/DT screen/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  makes/VBZ\n",
      "  (NP the/DT crab/JJ move/NN)\n",
      "  (NP a/DT little/JJ bit/NN)\n",
      "  to/TO\n",
      "  (NP the/DT right/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  When/WRB\n",
      "  we/PRP\n",
      "  click/VBP\n",
      "  the/DT\n",
      "  Act/NNP\n",
      "  (NP button/NN)\n",
      "  in/IN\n",
      "  the/DT\n",
      "  Greenfoot/NNP\n",
      "  (NP main/JJ window/NN)\n",
      "  ,/,\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  is/VBZ\n",
      "  executed/VBN\n",
      "  once/RB\n",
      "  ./.)\n",
      "(S\n",
      "  That/DT\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  (NP the/DT instruction/NN)\n",
      "  that/IN\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  written/VBN\n",
      "  inside/IN\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  (/(\n",
      "  move/VB\n",
      "  (/(\n",
      "  )/)\n",
      "  )/)\n",
      "  executes/VBZ\n",
      "  ./.)\n",
      "(S\n",
      "  Clicking/VBG\n",
      "  the/DT\n",
      "  Run/NNP\n",
      "  (NP button/NN)\n",
      "  is/VBZ\n",
      "  just/RB\n",
      "  like/IN\n",
      "  clicking/VBG\n",
      "  the/DT\n",
      "  Act/NNP\n",
      "  button/VBD\n",
      "  several/JJ\n",
      "  times/NNS\n",
      "  ,/,\n",
      "  very/RB\n",
      "  quickly/RB\n",
      "  ./.)\n",
      "(S\n",
      "  So/IN\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  is/VBZ\n",
      "  executed/VBN\n",
      "  over/IN\n",
      "  and/CC\n",
      "  over/RB\n",
      "  again/RB\n",
      "  ,/,\n",
      "  until/IN\n",
      "  we/PRP\n",
      "  click/VBP\n",
      "  Pause/NNP\n",
      "  ./.)\n",
      "(S\n",
      "  Terminology/NNP\n",
      "  (NP The/DT instruction/NN)\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  is/VBZ\n",
      "  called/VBN\n",
      "  (NP a/DT method/NN)\n",
      "  (NP call/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP A/DT method/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT action/NN)\n",
      "  that/IN\n",
      "  (NP an/DT object/NN)\n",
      "  knows/VBZ\n",
      "  how/WRB\n",
      "  to/TO\n",
      "  do/VB\n",
      "  (/(\n",
      "  here/RB\n",
      "  ,/,\n",
      "  (NP the/DT object/NN)\n",
      "  is/VBZ\n",
      "  (NP the/DT crab/NN)\n",
      "  )/)\n",
      "  and/CC\n",
      "  (NP a/DT method/NN)\n",
      "  (NP call/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT instruction/NN)\n",
      "  telling/VBG\n",
      "  (NP the/DT crab/NN)\n",
      "  to/TO\n",
      "  do/VB\n",
      "  it/PRP\n",
      "  ./.)\n",
      "(S\n",
      "  The/DT\n",
      "  parentheses/NNS\n",
      "  are/VBP\n",
      "  (NP part/NN)\n",
      "  of/IN\n",
      "  (NP the/DT method/NN)\n",
      "  (NP call/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Instructions/NNS\n",
      "  like/IN\n",
      "  (NP this/DT end/NN)\n",
      "  with/IN\n",
      "  (NP a/DT semicolon/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  (NP Additional/JJ information/NN)\n",
      "  can/MD\n",
      "  be/VB\n",
      "  passed/VBN\n",
      "  to/TO\n",
      "  some/DT\n",
      "  methods/NNS\n",
      "  within/IN\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT value/NN)\n",
      "  passed/VBN\n",
      "  is/VBZ\n",
      "  called/VBN\n",
      "  (NP a/DT parameter/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  2.3/CD\n",
      "  Turning/VBG\n",
      "  Let/VB\n",
      "  us/PRP\n",
      "  see/VB\n",
      "  what/WP\n",
      "  other/JJ\n",
      "  instructions/NNS\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  use/VB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT crab/NN)\n",
      "  also/RB\n",
      "  understands/VBZ\n",
      "  (NP a/DT turn/NN)\n",
      "  (NP instruction/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Here/RB\n",
      "  is/VBZ\n",
      "  what/WP\n",
      "  it/PRP\n",
      "  looks/VBZ\n",
      "  like/IN\n",
      "  :/:\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  (NP The/DT number/NN)\n",
      "  5/CD\n",
      "  in/IN\n",
      "  (NP the/DT instruction/NN)\n",
      "  specifies/VBZ\n",
      "  how/WRB\n",
      "  many/JJ\n",
      "  degrees/VBZ\n",
      "  (NP the/DT crab/NN)\n",
      "  should/MD\n",
      "  turn/VB\n",
      "  ./.)\n",
      "(S This/DT is/VBZ called/VBN (NP a/DT parameter/NN) ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  can/MD\n",
      "  also/RB\n",
      "  use/VB\n",
      "  other/JJ\n",
      "  numbers/NNS\n",
      "  ,/,\n",
      "  for/IN\n",
      "  (NP example/NN)\n",
      "  :/:\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  23/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  (NP The/DT degree/NN)\n",
      "  (NP value/NN)\n",
      "  is/VBZ\n",
      "  specified/VBN\n",
      "  out/IN\n",
      "  of/IN\n",
      "  360/CD\n",
      "  degrees/NNS\n",
      "  ,/,\n",
      "  so/IN\n",
      "  (NP any/DT value/NN)\n",
      "  between/IN\n",
      "  0/CD\n",
      "  and/CC\n",
      "  359/CD\n",
      "  can/MD\n",
      "  be/VB\n",
      "  used/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  Turning/VBG\n",
      "  360/CD\n",
      "  degrees/NNS\n",
      "  would/MD\n",
      "  turn/VB\n",
      "  all/PDT\n",
      "  (NP the/DT way/NN)\n",
      "  around/IN\n",
      "  ,/,\n",
      "  so/IN\n",
      "  it/PRP\n",
      "  is/VBZ\n",
      "  the/DT\n",
      "  same/JJ\n",
      "  as/IN\n",
      "  turning/VBG\n",
      "  0/CD\n",
      "  degrees/NNS\n",
      "  ,/,\n",
      "  or/CC\n",
      "  not/RB\n",
      "  turning/VBG\n",
      "  at/IN\n",
      "  all/DT\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  If/IN\n",
      "  we/PRP\n",
      "  want/VBP\n",
      "  to/TO\n",
      "  turn/VB\n",
      "  instead/RB\n",
      "  of/IN\n",
      "  moving/VBG\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  replace/VB\n",
      "  (NP the/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  with/IN\n",
      "  (NP a/DT turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  then/RB\n",
      "  looks/VBZ\n",
      "  like/IN\n",
      "  this/DT\n",
      "  :/:\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  Exercise/NNP\n",
      "  2.4/CD\n",
      "  Replace/NNP\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  with/IN\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  in/IN\n",
      "  your/PRP$\n",
      "  (NP scenario/NN)\n",
      "  ./.)\n",
      "(S Try/VB it/PRP out/RP ./.)\n",
      "(S\n",
      "  Also/RB\n",
      "  ,/,\n",
      "  try/VB\n",
      "  values/NNS\n",
      "  other/JJ\n",
      "  than/IN\n",
      "  5/CD\n",
      "  and/CC\n",
      "  see/VB\n",
      "  what/WP\n",
      "  it/PRP\n",
      "  looks/VBZ\n",
      "  like/IN\n",
      "  ./.)\n",
      "(S\n",
      "  Remember/NNP\n",
      "  :/:\n",
      "  (NP Every/DT time/NN)\n",
      "  you/PRP\n",
      "  change/VBP\n",
      "  your/PRP$\n",
      "  (NP source/NN)\n",
      "  (NP code/NN)\n",
      "  ,/,\n",
      "  you/PRP\n",
      "  must/MD\n",
      "  compile/VB\n",
      "  again/RB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.5/CD\n",
      "  How/WRB\n",
      "  can/MD\n",
      "  you/PRP\n",
      "  make/VB\n",
      "  (NP the/DT crab/NN)\n",
      "  (NP turn/NN)\n",
      "  left/VBD\n",
      "  ?/.)\n",
      "(S\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  Multiple/JJ\n",
      "  instructions/NNS\n",
      "  are/VBP\n",
      "  executed/VBN\n",
      "  in/IN\n",
      "  (NP sequence/NN)\n",
      "  ,/,\n",
      "  one/CD\n",
      "  after/IN\n",
      "  the/DT\n",
      "  other/JJ\n",
      "  ,/,\n",
      "  in/IN\n",
      "  (NP the/DT order/NN)\n",
      "  in/IN\n",
      "  which/WDT\n",
      "  they/PRP\n",
      "  are/VBP\n",
      "  written/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  20/CD\n",
      "  (NP |/JJ Chapter/NN)\n",
      "  2/CD\n",
      "  ■/IN\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  Code/NNP\n",
      "  2.2/CD\n",
      "  Making/VBG\n",
      "  (NP the/DT crab/NN)\n",
      "  (NP move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  (NP import/NN)\n",
      "  (NP greenfoot/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP */NN)\n",
      "  ;/:\n",
      "  ///NNP\n",
      "  (/(\n",
      "  World/NNP\n",
      "  ,/,\n",
      "  Actor/NNP\n",
      "  ,/,\n",
      "  GreenfootImage/NNP\n",
      "  ,/,\n",
      "  and/CC\n",
      "  Greenfoot/NNP\n",
      "  )/)\n",
      "  /**/VBP\n",
      "  */$\n",
      "  (NP This/DT class/NN)\n",
      "  defines/VBZ\n",
      "  (NP a/DT crab/NN)\n",
      "  ./.)\n",
      "(S Crabs/NNP live/VBP on/IN (NP the/DT beach/NN) ./.)\n",
      "(S\n",
      "  (NP *//JJ public/JJ class/NN)\n",
      "  Crab/NNP\n",
      "  extends/VBZ\n",
      "  Animal/NNP\n",
      "  {/(\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  ;/:\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  }/)\n",
      "  (NP The/DT next/JJ thing/NN)\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  try/VB\n",
      "  is/VBZ\n",
      "  to/TO\n",
      "  (NP both/DT move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT act/NN)\n",
      "  (NP method/NN)\n",
      "  can/MD\n",
      "  hold/VB\n",
      "  more/JJR\n",
      "  than/IN\n",
      "  one/CD\n",
      "  (NP instruction—we/NN)\n",
      "  can/MD\n",
      "  just/RB\n",
      "  write/VB\n",
      "  multiple/JJ\n",
      "  instructions/NNS\n",
      "  in/IN\n",
      "  (NP a/DT row/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Code/NNP\n",
      "  2.2/CD\n",
      "  shows/VBZ\n",
      "  the/DT\n",
      "  complete/JJ\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  ,/,\n",
      "  as/IN\n",
      "  it/PRP\n",
      "  looks/VBZ\n",
      "  when/WRB\n",
      "  we/PRP\n",
      "  move/VBP\n",
      "  and/CC\n",
      "  turn/VBP\n",
      "  ./.)\n",
      "(S\n",
      "  In/IN\n",
      "  (NP this/DT case/NN)\n",
      "  ,/,\n",
      "  at/IN\n",
      "  (NP every/DT act/JJ step/NN)\n",
      "  ,/,\n",
      "  (NP the/DT crab/NN)\n",
      "  will/MD\n",
      "  move/VB\n",
      "  and/CC\n",
      "  then/RB\n",
      "  turn/VB\n",
      "  (/(\n",
      "  but/CC\n",
      "  these/DT\n",
      "  actions/NNS\n",
      "  will/MD\n",
      "  happen/VB\n",
      "  so/RB\n",
      "  quickly/RB\n",
      "  after/IN\n",
      "  each/DT\n",
      "  other/JJ\n",
      "  that/IN\n",
      "  it/PRP\n",
      "  appears/VBZ\n",
      "  as/IN\n",
      "  if/IN\n",
      "  they/PRP\n",
      "  happen/VBP\n",
      "  at/IN\n",
      "  (NP the/DT same/JJ time/NN)\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.6/CD\n",
      "  (NP Use/NN)\n",
      "  (NP a/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  N/NNP\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  in/IN\n",
      "  your/PRP$\n",
      "  (NP crab’s/NN)\n",
      "  (NP act/NN)\n",
      "  (NP method/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Try/VB\n",
      "  different/JJ\n",
      "  values/NNS\n",
      "  for/IN\n",
      "  N./NNP\n",
      "  Terminology/NNP\n",
      "  (NP The/DT number/NN)\n",
      "  within/IN\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  in/IN\n",
      "  (NP the/DT turn/NN)\n",
      "  (NP instruction—that/NN)\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  the/DT\n",
      "  5/CD\n",
      "  in/IN\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  5/CD\n",
      "  )/)\n",
      "  (NP —is/NN)\n",
      "  called/VBD\n",
      "  (NP a/DT parameter/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP A/DT parameter/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT additional/JJ bit/NN)\n",
      "  of/IN\n",
      "  (NP information/NN)\n",
      "  that/IN\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  to/TO\n",
      "  provide/VB\n",
      "  when/WRB\n",
      "  we/PRP\n",
      "  call/VBP\n",
      "  some/DT\n",
      "  methods/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  Some/DT\n",
      "  methods/NNS\n",
      "  ,/,\n",
      "  like/IN\n",
      "  (NP move/NN)\n",
      "  ,/,\n",
      "  expect/VBP\n",
      "  no/DT\n",
      "  parameters/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  They/PRP\n",
      "  are/VBP\n",
      "  happy/JJ\n",
      "  to/TO\n",
      "  just/RB\n",
      "  execute/VB\n",
      "  as/RB\n",
      "  soon/RB\n",
      "  as/IN\n",
      "  we/PRP\n",
      "  write/VBP\n",
      "  (NP the/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Other/JJ\n",
      "  methods/NNS\n",
      "  ,/,\n",
      "  such/JJ\n",
      "  as/IN\n",
      "  (NP turn/NN)\n",
      "  ,/,\n",
      "  want/VBP\n",
      "  more/JJR\n",
      "  (NP information/NN)\n",
      "  :/:\n",
      "  How/WRB\n",
      "  much/JJ\n",
      "  should/MD\n",
      "  I/PRP\n",
      "  turn/VB\n",
      "  ?/.)\n",
      "(S\n",
      "  In/IN\n",
      "  (NP this/DT case/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  to/TO\n",
      "  provide/VB\n",
      "  (NP that/DT information/NN)\n",
      "  in/IN\n",
      "  (NP the/DT form/NN)\n",
      "  of/IN\n",
      "  (NP a/DT parameter/NN)\n",
      "  (NP value/NN)\n",
      "  within/IN\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  ,/,\n",
      "  for/IN\n",
      "  (NP instance/NN)\n",
      "  ,/,\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  17/CD\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  2.4/CD\n",
      "  Dealing/VBG\n",
      "  with/IN\n",
      "  screen/JJ\n",
      "  edges/NNS\n",
      "  |/VBP\n",
      "  21/CD\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  When/WRB\n",
      "  (NP a/DT class/NN)\n",
      "  is/VBZ\n",
      "  compiled/VBN\n",
      "  ,/,\n",
      "  (NP the/DT compiler/NN)\n",
      "  checks/NNS\n",
      "  to/TO\n",
      "  see/VB\n",
      "  whether/IN\n",
      "  there/EX\n",
      "  are/VBP\n",
      "  any/DT\n",
      "  errors/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  (NP an/DT error/NN)\n",
      "  is/VBZ\n",
      "  found/VBN\n",
      "  ,/,\n",
      "  (NP an/DT error/NN)\n",
      "  (NP message/NN)\n",
      "  is/VBZ\n",
      "  displayed/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Side/JJ note/NN)\n",
      "  :/:\n",
      "  Errors/NNS\n",
      "  When/WRB\n",
      "  we/PRP\n",
      "  write/VBP\n",
      "  (NP source/NN)\n",
      "  (NP code/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  to/TO\n",
      "  be/VB\n",
      "  very/RB\n",
      "  (NP careful—every/JJ single/JJ character/NN)\n",
      "  counts/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  Getting/VBG\n",
      "  one/CD\n",
      "  (NP small/JJ thing/NN)\n",
      "  wrong/JJ\n",
      "  will/MD\n",
      "  result/VB\n",
      "  in/IN\n",
      "  our/PRP$\n",
      "  (NP program/NN)\n",
      "  not/RB\n",
      "  working/VBG\n",
      "  ./.)\n",
      "(S Usually/RB ,/, it/PRP will/MD not/RB compile/VB ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  will/MD\n",
      "  happen/VB\n",
      "  to/TO\n",
      "  us/PRP\n",
      "  regularly/RB\n",
      "  :/:\n",
      "  When/WRB\n",
      "  we/PRP\n",
      "  write/VBP\n",
      "  programs/NNS\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  inevitably/RB\n",
      "  make/VBP\n",
      "  mistakes/NNS\n",
      "  ,/,\n",
      "  and/CC\n",
      "  then/RB\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  to/TO\n",
      "  correct/VB\n",
      "  them/PRP\n",
      "  ./.)\n",
      "(S Let/VB us/PRP try/VB that/IN out/RB now/RB ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  ,/,\n",
      "  for/IN\n",
      "  (NP example/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  forget/VBP\n",
      "  to/TO\n",
      "  write/VB\n",
      "  (NP the/DT semicolon/NN)\n",
      "  after/IN\n",
      "  (NP the/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP instruction/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  will/MD\n",
      "  be/VB\n",
      "  told/VBN\n",
      "  about/IN\n",
      "  it/PRP\n",
      "  when/WRB\n",
      "  we/PRP\n",
      "  try/VBP\n",
      "  to/TO\n",
      "  compile/VB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.7/CD\n",
      "  Open/NNP\n",
      "  your/PRP$\n",
      "  (NP editor/NN)\n",
      "  to/TO\n",
      "  show/VB\n",
      "  (NP the/DT crab’s/NN)\n",
      "  (NP source/NN)\n",
      "  (NP code/NN)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  remove/VB\n",
      "  (NP the/DT semicolon/NN)\n",
      "  after/IN\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  ./.)\n",
      "(S Then/RB (NP compile/NN) ./.)\n",
      "(S\n",
      "  Also/RB\n",
      "  (NP experiment/NN)\n",
      "  with/IN\n",
      "  other/JJ\n",
      "  errors/NNS\n",
      "  ,/,\n",
      "  such/JJ\n",
      "  as/IN\n",
      "  misspelling/VBG\n",
      "  (NP move/NN)\n",
      "  or/CC\n",
      "  making/VBG\n",
      "  other/JJ\n",
      "  random/JJ\n",
      "  changes/NNS\n",
      "  to/TO\n",
      "  (NP the/DT code/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Make/NNP\n",
      "  sure/JJ\n",
      "  to/TO\n",
      "  change/VB\n",
      "  it/PRP\n",
      "  all/DT\n",
      "  back/RB\n",
      "  after/IN\n",
      "  (NP this/DT exercise/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.8/CD\n",
      "  Make/NNP\n",
      "  various/JJ\n",
      "  changes/NNS\n",
      "  to/TO\n",
      "  cause/VB\n",
      "  (NP different/JJ error/NN)\n",
      "  messages/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  Find/NNP\n",
      "  at/IN\n",
      "  least/JJS\n",
      "  five/CD\n",
      "  (NP different/JJ error/NN)\n",
      "  messages/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  Write/NNP\n",
      "  down/RP\n",
      "  (NP each/DT error/NN)\n",
      "  (NP message/NN)\n",
      "  and/CC\n",
      "  what/WP\n",
      "  (NP change/NN)\n",
      "  you/PRP\n",
      "  introduced/VBD\n",
      "  to/TO\n",
      "  provoke/VB\n",
      "  (NP this/DT error/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Tip/NN)\n",
      "  :/:\n",
      "  When/WRB\n",
      "  (NP an/DT error/NN)\n",
      "  (NP message/NN)\n",
      "  appears/VBZ\n",
      "  at/IN\n",
      "  (NP the/DT bottom/NN)\n",
      "  of/IN\n",
      "  (NP the/DT editor/NN)\n",
      "  (NP window/NN)\n",
      "  ,/,\n",
      "  (NP a/DT question/NN)\n",
      "  (NP mark/NN)\n",
      "  (NP button/NN)\n",
      "  appears/VBZ\n",
      "  to/TO\n",
      "  (NP the/DT right/NN)\n",
      "  of/IN\n",
      "  it/PRP\n",
      "  ./.)\n",
      "(S\n",
      "  Clicking/VBG\n",
      "  (NP this/DT button/NN)\n",
      "  displays/VBZ\n",
      "  (NP some/DT additional/JJ information/NN)\n",
      "  about/IN\n",
      "  (NP the/DT error/NN)\n",
      "  (NP message/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  As/IN\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  see/VB\n",
      "  with/IN\n",
      "  (NP this/DT exercise/NN)\n",
      "  ,/,\n",
      "  if/IN\n",
      "  we/PRP\n",
      "  get/VBP\n",
      "  one/CD\n",
      "  (NP small/JJ detail/NN)\n",
      "  wrong/JJ\n",
      "  ,/,\n",
      "  Greenfoot/NNP\n",
      "  will/MD\n",
      "  open/VB\n",
      "  (NP the/DT editor/NN)\n",
      "  ,/,\n",
      "  highlight/VBD\n",
      "  (NP a/DT line/NN)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  display/VB\n",
      "  (NP a/DT message/NN)\n",
      "  at/IN\n",
      "  (NP the/DT bottom/NN)\n",
      "  of/IN\n",
      "  (NP the/DT editor/NN)\n",
      "  (NP window/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP This/DT message/NN)\n",
      "  attempts/VBZ\n",
      "  to/TO\n",
      "  explain/VB\n",
      "  (NP the/DT error/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  The/DT\n",
      "  messages/NNS\n",
      "  ,/,\n",
      "  however/RB\n",
      "  ,/,\n",
      "  vary/JJ\n",
      "  considerably/RB\n",
      "  in/IN\n",
      "  their/PRP$\n",
      "  (NP accuracy/NN)\n",
      "  and/CC\n",
      "  (NP usefulness/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Sometimes/RB\n",
      "  they/PRP\n",
      "  tell/VBP\n",
      "  us/PRP\n",
      "  fairly/RB\n",
      "  accurately/RB\n",
      "  what/WP\n",
      "  (NP the/DT problem/NN)\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  but/CC\n",
      "  sometimes/RB\n",
      "  they/PRP\n",
      "  are/VBP\n",
      "  cryptic/JJ\n",
      "  and/CC\n",
      "  hard/JJ\n",
      "  to/TO\n",
      "  understand/VB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT line/NN)\n",
      "  that/WDT\n",
      "  is/VBZ\n",
      "  highlighted/VBN\n",
      "  is/VBZ\n",
      "  often/RB\n",
      "  (NP the/DT line/NN)\n",
      "  where/WRB\n",
      "  (NP the/DT problem/NN)\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  but/CC\n",
      "  sometimes/VBZ\n",
      "  it/PRP\n",
      "  is/VBZ\n",
      "  (NP the/DT line/NN)\n",
      "  after/IN\n",
      "  (NP the/DT problem/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  When/WRB\n",
      "  you/PRP\n",
      "  see/VBP\n",
      "  ,/,\n",
      "  for/IN\n",
      "  (NP example/NN)\n",
      "  ,/,\n",
      "  (NP a/DT “/NN)\n",
      "  ;/:\n",
      "  expected”/CC\n",
      "  (NP message/NN)\n",
      "  ,/,\n",
      "  it/PRP\n",
      "  is/VBZ\n",
      "  possible/JJ\n",
      "  that/IN\n",
      "  (NP the/DT semicolon/NN)\n",
      "  is/VBZ\n",
      "  in/IN\n",
      "  (NP fact/NN)\n",
      "  missing/VBG\n",
      "  on/IN\n",
      "  (NP the/DT line/NN)\n",
      "  above/IN\n",
      "  (NP the/DT highlighted/JJ line/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  will/MD\n",
      "  learn/VB\n",
      "  to/TO\n",
      "  read/VB\n",
      "  these/DT\n",
      "  messages/NNS\n",
      "  a/DT\n",
      "  little/JJ\n",
      "  better/JJR\n",
      "  over/IN\n",
      "  (NP time/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  For/IN\n",
      "  now/RB\n",
      "  ,/,\n",
      "  if/IN\n",
      "  you/PRP\n",
      "  get/VBP\n",
      "  (NP a/DT message/NN)\n",
      "  and/CC\n",
      "  you/PRP\n",
      "  are/VBP\n",
      "  unsure/JJ\n",
      "  what/WP\n",
      "  it/PRP\n",
      "  means/VBZ\n",
      "  ,/,\n",
      "  look/VB\n",
      "  very/RB\n",
      "  carefully/RB\n",
      "  at/IN\n",
      "  your/PRP$\n",
      "  (NP code/NN)\n",
      "  and/CC\n",
      "  check/VB\n",
      "  that/IN\n",
      "  you/PRP\n",
      "  have/VBP\n",
      "  typed/VBN\n",
      "  (NP everything/NN)\n",
      "  correctly/RB\n",
      "  ./.)\n",
      "(S\n",
      "  2.4/CD\n",
      "  Dealing/VBG\n",
      "  with/IN\n",
      "  screen/JJ\n",
      "  edges/NNS\n",
      "  When/WRB\n",
      "  we/PRP\n",
      "  made/VBD\n",
      "  (NP the/DT crabs/JJ move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  in/IN\n",
      "  the/DT\n",
      "  previous/JJ\n",
      "  sections/NNS\n",
      "  ,/,\n",
      "  they/PRP\n",
      "  got/VBD\n",
      "  stuck/VBN\n",
      "  when/WRB\n",
      "  they/PRP\n",
      "  reached/VBD\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT screen/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  Greenfoot/NNP\n",
      "  is/VBZ\n",
      "  designed/VBN\n",
      "  so/RB\n",
      "  that/IN\n",
      "  actors/NNS\n",
      "  can/MD\n",
      "  not/RB\n",
      "  leave/VB\n",
      "  (NP the/DT world/NN)\n",
      "  and/CC\n",
      "  fall/VB\n",
      "  off/RP\n",
      "  its/PRP$\n",
      "  (NP edge/NN)\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  Now/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  shall/MD\n",
      "  improve/VB\n",
      "  (NP this/DT behavior/NN)\n",
      "  so/RB\n",
      "  that/IN\n",
      "  (NP the/DT crab/NN)\n",
      "  notices/VBZ\n",
      "  that/IN\n",
      "  it/PRP\n",
      "  has/VBZ\n",
      "  reached/VBN\n",
      "  (NP the/DT world/NN)\n",
      "  (NP edge/NN)\n",
      "  and/CC\n",
      "  turns/VBZ\n",
      "  around/RB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT question/NN)\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  How/WRB\n",
      "  can/MD\n",
      "  we/PRP\n",
      "  do/VB\n",
      "  that/DT\n",
      "  ?/.)\n",
      "(S\n",
      "  22/CD\n",
      "  (NP |/JJ Chapter/NN)\n",
      "  2/CD\n",
      "  ■/IN\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  Exercise/NNP\n",
      "  2.9/CD\n",
      "  Open/NNP\n",
      "  (NP the/DT editor/NN)\n",
      "  for/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S (NP Switch/NN) to/TO Documentation/NNP (NP view/NN) ./.)\n",
      "(S\n",
      "  Find/IN\n",
      "  (NP the/DT list/NN)\n",
      "  of/IN\n",
      "  methods/NNS\n",
      "  for/IN\n",
      "  (NP this/DT class/NN)\n",
      "  (/(\n",
      "  the/DT\n",
      "  “Method/NNP\n",
      "  Summary”/NNP\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  How/WRB\n",
      "  many/JJ\n",
      "  methods/NNS\n",
      "  does/VBZ\n",
      "  (NP this/DT class/NN)\n",
      "  have/VB\n",
      "  ?/.)\n",
      "(S\n",
      "  Above/NNP\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  used/VBN\n",
      "  (NP the/DT move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  methods/NNS\n",
      "  ,/,\n",
      "  so/IN\n",
      "  there/EX\n",
      "  might/MD\n",
      "  also/RB\n",
      "  be/VB\n",
      "  (NP a/DT method/NN)\n",
      "  that/WDT\n",
      "  helps/VBZ\n",
      "  us/PRP\n",
      "  with/IN\n",
      "  our/PRP$\n",
      "  (NP new/JJ goal/NN)\n",
      "  ./.)\n",
      "(S (/( In/IN (NP fact/NN) ,/, there/EX is/VBZ ./. )/))\n",
      "(S\n",
      "  But/CC\n",
      "  how/WRB\n",
      "  do/VBP\n",
      "  we/PRP\n",
      "  find/VB\n",
      "  out/RP\n",
      "  what/WP\n",
      "  methods/IN\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  got/VBN\n",
      "  available/JJ\n",
      "  ?/.)\n",
      "(S\n",
      "  (NP The/DT move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  methods/NNS\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  used/VBN\n",
      "  so/RB\n",
      "  far/RB\n",
      "  come/VBN\n",
      "  from/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP A/DT crab/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT animal/NN)\n",
      "  (/(\n",
      "  signified/VBN\n",
      "  by/IN\n",
      "  (NP the/DT arrow/NN)\n",
      "  that/WDT\n",
      "  goes/VBZ\n",
      "  from/IN\n",
      "  Crab/NNP\n",
      "  to/TO\n",
      "  Animal/NNP\n",
      "  in/IN\n",
      "  (NP the/DT class/NN)\n",
      "  (NP diagram/NN)\n",
      "  )/)\n",
      "  ,/,\n",
      "  therefore/IN\n",
      "  it/PRP\n",
      "  can/MD\n",
      "  do/VB\n",
      "  whatever/WDT\n",
      "  (NP an/DT animal/NN)\n",
      "  can/MD\n",
      "  do/VB\n",
      "  ./.)\n",
      "(S\n",
      "  Our/PRP$\n",
      "  (NP Animal/JJ class/NN)\n",
      "  knows/VBZ\n",
      "  how/WRB\n",
      "  to/TO\n",
      "  move/VB\n",
      "  and/CC\n",
      "  turn—that/DT\n",
      "  is/VBZ\n",
      "  why/WRB\n",
      "  our/PRP$\n",
      "  (NP crab/NN)\n",
      "  can/MD\n",
      "  also/RB\n",
      "  do/VB\n",
      "  it/PRP\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  is/VBZ\n",
      "  called/VBN\n",
      "  (NP inheritance/NN)\n",
      "  :/:\n",
      "  The/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  inherits/VBZ\n",
      "  all/PDT\n",
      "  the/DT\n",
      "  abilities/NNS\n",
      "  (/(\n",
      "  methods/NNS\n",
      "  )/)\n",
      "  from/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT question/NN)\n",
      "  now/RB\n",
      "  is/VBZ\n",
      "  ,/,\n",
      "  what/WP\n",
      "  else/RB\n",
      "  can/MD\n",
      "  our/PRP$\n",
      "  animals/NNS\n",
      "  do/VB\n",
      "  ?/.)\n",
      "(S\n",
      "  To/TO\n",
      "  investigate/VB\n",
      "  this/DT\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  open/VB\n",
      "  (NP the/DT editor/NN)\n",
      "  for/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT editor/NN)\n",
      "  can/MD\n",
      "  display/VB\n",
      "  two/CD\n",
      "  different/JJ\n",
      "  views/NNS\n",
      "  :/:\n",
      "  It/PRP\n",
      "  can/MD\n",
      "  show/VB\n",
      "  (NP the/DT source/NN)\n",
      "  (NP code/NN)\n",
      "  (/(\n",
      "  as/IN\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  seen/VBN\n",
      "  for/IN\n",
      "  the/DT\n",
      "  Crab/NNP\n",
      "  (NP class/NN)\n",
      "  )/)\n",
      "  or/CC\n",
      "  it/PRP\n",
      "  can/MD\n",
      "  show/VB\n",
      "  (NP the/DT documentation/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT view/NN)\n",
      "  can/MD\n",
      "  be/VB\n",
      "  switched/VBN\n",
      "  using/VBG\n",
      "  (NP a/DT popup/JJ selection/NN)\n",
      "  (NP menu/NN)\n",
      "  in/IN\n",
      "  (NP the/DT top/JJ right/NN)\n",
      "  (NP corner/NN)\n",
      "  of/IN\n",
      "  (NP the/DT editor/NN)\n",
      "  (NP window/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  now/RB\n",
      "  want/VBP\n",
      "  to/TO\n",
      "  look/VB\n",
      "  at/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  in/IN\n",
      "  the/DT\n",
      "  Documentation/NNP\n",
      "  (NP view/NN)\n",
      "  (/(\n",
      "  Figure/NNP\n",
      "  2.3/CD\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  Method/NNP\n",
      "  summary/JJ\n",
      "  View/NNP\n",
      "  (NP switch/NN)\n",
      "  (NP Figure/NN)\n",
      "  2.3/CD\n",
      "  Documentation/NNP\n",
      "  (NP view/NN)\n",
      "  (/(\n",
      "  with/IN\n",
      "  (NP method/NN)\n",
      "  (NP summary/NN)\n",
      "  )/)\n",
      "  of/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  Concept/NNP\n",
      "  :/:\n",
      "  (NP A/DT subclass/NN)\n",
      "  inherits/VBZ\n",
      "  all/PDT\n",
      "  the/DT\n",
      "  methods/NNS\n",
      "  from/IN\n",
      "  its/PRP$\n",
      "  (NP superclass/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  That/DT\n",
      "  means/VBZ\n",
      "  that/IN\n",
      "  it/PRP\n",
      "  has/VBZ\n",
      "  and/CC\n",
      "  can/MD\n",
      "  use/VB\n",
      "  all/DT\n",
      "  methods/NNS\n",
      "  that/IN\n",
      "  its/PRP$\n",
      "  (NP superclass/NN)\n",
      "  defines/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  2.4/CD\n",
      "  Dealing/VBG\n",
      "  with/IN\n",
      "  screen/JJ\n",
      "  edges/NNS\n",
      "  |/VBP\n",
      "  23/CD\n",
      "  If/IN\n",
      "  we/PRP\n",
      "  look/VBP\n",
      "  at/IN\n",
      "  (NP the/DT method/NN)\n",
      "  (NP summary/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  see/VB\n",
      "  all/PDT\n",
      "  the/DT\n",
      "  methods/NNS\n",
      "  that/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  provides/VBZ\n",
      "  ./.)\n",
      "(S\n",
      "  Among/IN\n",
      "  them/PRP\n",
      "  are/VBP\n",
      "  three/CD\n",
      "  methods/NNS\n",
      "  that/WDT\n",
      "  are/VBP\n",
      "  especially/RB\n",
      "  interesting/VBG\n",
      "  to/TO\n",
      "  us/PRP\n",
      "  at/IN\n",
      "  (NP the/DT moment/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  They/PRP\n",
      "  are/VBP\n",
      "  :/:\n",
      "  (NP boolean/JJ atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  Test/VBP\n",
      "  if/IN\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  close/JJ\n",
      "  to/TO\n",
      "  one/CD\n",
      "  of/IN\n",
      "  the/DT\n",
      "  edges/NNS\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP void/JJ move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  Move/NNP\n",
      "  forward/RB\n",
      "  in/IN\n",
      "  (NP the/DT current/JJ direction/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP void/JJ turn/NN)\n",
      "  (/(\n",
      "  (NP int/JJ angle/NN)\n",
      "  )/)\n",
      "  Turn/NNP\n",
      "  “angle”/NNP\n",
      "  degrees/VBZ\n",
      "  toward/IN\n",
      "  (NP the/DT right/NN)\n",
      "  (/(\n",
      "  (NP clockwise/NN)\n",
      "  )/)\n",
      "  ./.)\n",
      "(S\n",
      "  Here/RB\n",
      "  we/PRP\n",
      "  see/VBP\n",
      "  the/DT\n",
      "  signatures/NNS\n",
      "  for/IN\n",
      "  three/CD\n",
      "  methods/NNS\n",
      "  ,/,\n",
      "  as/IN\n",
      "  we/PRP\n",
      "  first/RB\n",
      "  encountered/VBD\n",
      "  them/PRP\n",
      "  in/IN\n",
      "  (NP Chapter/NN)\n",
      "  1/CD\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Each/DT method/NN)\n",
      "  (NP signature/NN)\n",
      "  starts/VBZ\n",
      "  with/IN\n",
      "  (NP a/DT return/NN)\n",
      "  (NP type/NN)\n",
      "  and/CC\n",
      "  is/VBZ\n",
      "  followed/VBN\n",
      "  by/IN\n",
      "  (NP the/DT method/NN)\n",
      "  (NP name/NN)\n",
      "  and/CC\n",
      "  (NP the/DT parameter/NN)\n",
      "  (NP list/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Below/IN\n",
      "  it/PRP\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  see/VBP\n",
      "  (NP a/DT comment/NN)\n",
      "  describing/VBG\n",
      "  what/WP\n",
      "  (NP the/DT method/NN)\n",
      "  does/VBZ\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  can/MD\n",
      "  see/VB\n",
      "  that/IN\n",
      "  the/DT\n",
      "  three/CD\n",
      "  (NP method/NN)\n",
      "  names/NNS\n",
      "  are/VBP\n",
      "  (NP atWorldEdge/NN)\n",
      "  ,/,\n",
      "  (NP move/NN)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  methods/NNS\n",
      "  are/VBP\n",
      "  the/DT\n",
      "  ones/NNS\n",
      "  we/PRP\n",
      "  used/VBD\n",
      "  in/IN\n",
      "  the/DT\n",
      "  previous/JJ\n",
      "  sections/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  we/PRP\n",
      "  look/VBP\n",
      "  at/IN\n",
      "  their/PRP$\n",
      "  (NP parameter/NN)\n",
      "  lists/NNS\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  see/VB\n",
      "  what/WP\n",
      "  we/PRP\n",
      "  observed/VBD\n",
      "  before/IN\n",
      "  :/:\n",
      "  (NP move/NN)\n",
      "  has/VBZ\n",
      "  no/DT\n",
      "  parameters/NNS\n",
      "  (/(\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  are/VBP\n",
      "  empty/JJ\n",
      "  )/)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  turn/VB\n",
      "  expects/VBZ\n",
      "  one/CD\n",
      "  (NP parameter/NN)\n",
      "  of/IN\n",
      "  (NP type/NN)\n",
      "  (NP int/NN)\n",
      "  (/(\n",
      "  (NP a/DT whole/JJ number/NN)\n",
      "  )/)\n",
      "  for/IN\n",
      "  (NP the/DT angle/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  (NP Read/JJ Section/NN)\n",
      "  1.5/CD\n",
      "  again/RB\n",
      "  if/IN\n",
      "  you/PRP\n",
      "  are/VBP\n",
      "  unsure/JJ\n",
      "  about/IN\n",
      "  (NP parameter/NN)\n",
      "  lists/NNS\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  We/PRP\n",
      "  can/MD\n",
      "  also/RB\n",
      "  see/VB\n",
      "  that/IN\n",
      "  (NP the/DT move/NN)\n",
      "  and/CC\n",
      "  (NP turn/NN)\n",
      "  methods/NNS\n",
      "  have/VBP\n",
      "  void/VBN\n",
      "  as/IN\n",
      "  their/PRP$\n",
      "  (NP return/NN)\n",
      "  (NP type/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  means/VBZ\n",
      "  that/IN\n",
      "  (NP neither/DT method/NN)\n",
      "  returns/VBZ\n",
      "  (NP a/DT value/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  are/VBP\n",
      "  commanding/VBG\n",
      "  or/CC\n",
      "  instructing/VBG\n",
      "  (NP the/DT object/NN)\n",
      "  to/TO\n",
      "  move/VB\n",
      "  or/CC\n",
      "  to/TO\n",
      "  turn/VB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT animal/NN)\n",
      "  will/MD\n",
      "  just/RB\n",
      "  obey/VB\n",
      "  (NP the/DT command/NN)\n",
      "  but/CC\n",
      "  not/RB\n",
      "  respond/VB\n",
      "  with/IN\n",
      "  (NP an/DT answer/NN)\n",
      "  to/TO\n",
      "  us/PRP\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT signature/NN)\n",
      "  for/IN\n",
      "  (NP atWorldEdge/NN)\n",
      "  is/VBZ\n",
      "  a/DT\n",
      "  little/JJ\n",
      "  different/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  It/PRP\n",
      "  is/VBZ\n",
      "  (NP boolean/JJ atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP This/DT method/NN)\n",
      "  has/VBZ\n",
      "  no/DT\n",
      "  parameters/NNS\n",
      "  (/(\n",
      "  there/EX\n",
      "  is/VBZ\n",
      "  (NP nothing/NN)\n",
      "  within/IN\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  )/)\n",
      "  ,/,\n",
      "  but/CC\n",
      "  it/PRP\n",
      "  specifies/VBZ\n",
      "  (NP a/DT return/NN)\n",
      "  (NP value/NN)\n",
      "  :/:\n",
      "  (NP boolean/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  have/VBP\n",
      "  briefly/VBN\n",
      "  encountered/VBD\n",
      "  (NP the/DT boolean/JJ type/NN)\n",
      "  in/IN\n",
      "  Section/NNP\n",
      "  1.4—it/CD\n",
      "  is/VBZ\n",
      "  (NP a/DT type/NN)\n",
      "  that/WDT\n",
      "  can/MD\n",
      "  hold/VB\n",
      "  two/CD\n",
      "  possible/JJ\n",
      "  values/NNS\n",
      "  :/:\n",
      "  true/JJ\n",
      "  or/CC\n",
      "  false/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  Calling/VBG\n",
      "  methods/NNS\n",
      "  that/WDT\n",
      "  have/VBP\n",
      "  return/VBN\n",
      "  values/NNS\n",
      "  (/(\n",
      "  where/WRB\n",
      "  (NP the/DT return/NN)\n",
      "  (NP type/NN)\n",
      "  is/VBZ\n",
      "  not/RB\n",
      "  void/JJ\n",
      "  )/)\n",
      "  is/VBZ\n",
      "  not/RB\n",
      "  like/IN\n",
      "  issuing/VBG\n",
      "  (NP a/DT command/NN)\n",
      "  ,/,\n",
      "  but/CC\n",
      "  asking/VBG\n",
      "  (NP a/DT question/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  we/PRP\n",
      "  use/VBP\n",
      "  (NP the/DT atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP method/NN)\n",
      "  ,/,\n",
      "  (NP the/DT method/NN)\n",
      "  will/MD\n",
      "  respond/VB\n",
      "  with/IN\n",
      "  either/DT\n",
      "  true/JJ\n",
      "  (/(\n",
      "  Yes/UH\n",
      "  !/.\n",
      "  )/))\n",
      "(S or/CC false/JJ (/( No/UH !/. )/) ./.)\n",
      "(S\n",
      "  Thus/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  can/MD\n",
      "  use/VB\n",
      "  (NP this/DT method/NN)\n",
      "  to/TO\n",
      "  check/VB\n",
      "  whether/IN\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  at/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ./.)\n",
      "(S Exercise/RB 2.10/CD Create/NNP (NP a/DT crab/NN) ./.)\n",
      "(S\n",
      "  Right-click/JJ\n",
      "  it/PRP\n",
      "  ,/,\n",
      "  and/CC\n",
      "  find/VB\n",
      "  (NP the/DT boolean/JJ atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP method/NN)\n",
      "  (/(\n",
      "  it/PRP\n",
      "  is/VBZ\n",
      "  in/IN\n",
      "  the/DT\n",
      "  inherited/VBN\n",
      "  from/IN\n",
      "  Animal/NNP\n",
      "  (NP submenu/NN)\n",
      "  ,/,\n",
      "  since/IN\n",
      "  (NP the/DT crab/NN)\n",
      "  inherited/VBD\n",
      "  (NP this/DT method/NN)\n",
      "  from/IN\n",
      "  the/DT\n",
      "  Animal/NNP\n",
      "  (NP class/NN)\n",
      "  )/)\n",
      "  ./.)\n",
      "(S Call/VB (NP this/DT method/NN) ./.)\n",
      "(S What/WP does/VBZ it/PRP return/VB ?/.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.11/CD\n",
      "  Let/VBD\n",
      "  (NP the/DT crab/NN)\n",
      "  (NP run/NN)\n",
      "  to/TO\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT screen/NN)\n",
      "  (/(\n",
      "  or/CC\n",
      "  move/VB\n",
      "  it/PRP\n",
      "  there/RB\n",
      "  manually/RB\n",
      "  )/)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  then/RB\n",
      "  call/VB\n",
      "  (NP the/DT atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP method/NN)\n",
      "  again/RB\n",
      "  ./.)\n",
      "(S What/WP does/VBZ it/PRP return/VB now/RB ?/.)\n",
      "(S\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  Calling/VBG\n",
      "  (NP a/DT method/NN)\n",
      "  with/IN\n",
      "  (NP a/DT void/JJ return/NN)\n",
      "  (NP type/NN)\n",
      "  issues/NNS\n",
      "  (NP a/DT command/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Calling/VBG\n",
      "  (NP a/DT method/NN)\n",
      "  with/IN\n",
      "  (NP a/DT non-void/JJ return/NN)\n",
      "  (NP type/NN)\n",
      "  asks/VBZ\n",
      "  (NP a/DT question/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Concept/NN)\n",
      "  :/:\n",
      "  An/DT\n",
      "  if-statement/JJ\n",
      "  can/MD\n",
      "  be/VB\n",
      "  used/VBN\n",
      "  to/TO\n",
      "  write/VB\n",
      "  instructions/NNS\n",
      "  that/WDT\n",
      "  are/VBP\n",
      "  executed/VBN\n",
      "  only/RB\n",
      "  when/WRB\n",
      "  (NP a/DT certain/JJ condition/NN)\n",
      "  is/VBZ\n",
      "  true/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  24/CD\n",
      "  (NP |/JJ Chapter/NN)\n",
      "  2/CD\n",
      "  ■/IN\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  Code/NNP\n",
      "  2.3/CD\n",
      "  Turning/VBG\n",
      "  around/RB\n",
      "  at/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  (NP import/NN)\n",
      "  (NP greenfoot/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP */NN)\n",
      "  ;/:\n",
      "  ///NNP\n",
      "  (/(\n",
      "  World/NNP\n",
      "  ,/,\n",
      "  Actor/NNP\n",
      "  ,/,\n",
      "  GreenfootImage/NNP\n",
      "  ,/,\n",
      "  and/CC\n",
      "  Greenfoot/NNP\n",
      "  )/)\n",
      "  /**/VBP\n",
      "  */$\n",
      "  (NP This/DT class/NN)\n",
      "  defines/VBZ\n",
      "  (NP a/DT crab/NN)\n",
      "  ./.)\n",
      "(S Crabs/NNP live/VBP on/IN (NP the/DT beach/NN) ./.)\n",
      "(S\n",
      "  (NP *//JJ public/JJ class/NN)\n",
      "  Crab/NNP\n",
      "  extends/VBZ\n",
      "  Animal/NNP\n",
      "  {/(\n",
      "  (NP public/JJ void/NN)\n",
      "  (NP act/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  {/(\n",
      "  if/IN\n",
      "  (/(\n",
      "  (NP atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  17/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  move/FW\n",
      "  (/(\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  }/)\n",
      "  The/DT\n",
      "  if-statement/JJ\n",
      "  is/VBZ\n",
      "  (NP a/DT part/NN)\n",
      "  of/IN\n",
      "  the/DT\n",
      "  Java/NNP\n",
      "  (NP language/NN)\n",
      "  that/WDT\n",
      "  makes/VBZ\n",
      "  it/PRP\n",
      "  possible/JJ\n",
      "  to/TO\n",
      "  execute/VB\n",
      "  commands/NNS\n",
      "  only/RB\n",
      "  if/IN\n",
      "  (NP some/DT condition/NN)\n",
      "  is/VBZ\n",
      "  true/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  For/IN\n",
      "  (NP example/NN)\n",
      "  ,/,\n",
      "  here/RB\n",
      "  we/PRP\n",
      "  want/VBP\n",
      "  to/TO\n",
      "  turn/VB\n",
      "  only/RB\n",
      "  if/IN\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  near/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT code/NN)\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  written/VBN\n",
      "  is/VBZ\n",
      "  :/:\n",
      "  if/IN\n",
      "  (/(\n",
      "  (NP atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP turn/NN)\n",
      "  (/(\n",
      "  17/CD\n",
      "  )/)\n",
      "  ;/:\n",
      "  }/)\n",
      "  move/FW\n",
      "  (/(\n",
      "  )/)\n",
      "  ;/:\n",
      "  (NP The/DT general/JJ form/NN)\n",
      "  of/IN\n",
      "  (NP an/DT if-statement/NN)\n",
      "  is/VBZ\n",
      "  this/DT\n",
      "  :/:\n",
      "  if/IN\n",
      "  (/(\n",
      "  (NP condition/NN)\n",
      "  )/)\n",
      "  {/(\n",
      "  (NP instruction/NN)\n",
      "  ;/:\n",
      "  (NP instruction/NN)\n",
      "  ;/:\n",
      "  .../:\n",
      "  }/)\n",
      "  In/IN\n",
      "  (NP place/NN)\n",
      "  of/IN\n",
      "  (NP the/DT condition/NN)\n",
      "  can/MD\n",
      "  be/VB\n",
      "  (NP any/DT expression/NN)\n",
      "  that/WDT\n",
      "  is/VBZ\n",
      "  either/DT\n",
      "  true/JJ\n",
      "  or/CC\n",
      "  false/JJ\n",
      "  (/(\n",
      "  such/JJ\n",
      "  as/IN\n",
      "  our/PRP$\n",
      "  (NP atWorldEdge/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  method/VBP\n",
      "  (NP call/NN)\n",
      "  )/)\n",
      "  ,/,\n",
      "  and/CC\n",
      "  the/DT\n",
      "  instructions/NNS\n",
      "  will/MD\n",
      "  be/VB\n",
      "  executed/VBN\n",
      "  only/RB\n",
      "  if/IN\n",
      "  (NP the/DT condition/NN)\n",
      "  is/VBZ\n",
      "  true/JJ\n",
      "  ./.)\n",
      "(S There/EX can/MD be/VB one/CD or/CC more/JJR instructions/NNS ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  (NP the/DT condition/NN)\n",
      "  is/VBZ\n",
      "  false/JJ\n",
      "  ,/,\n",
      "  the/DT\n",
      "  instructions/NNS\n",
      "  are/VBP\n",
      "  just/RB\n",
      "  skipped/VBN\n",
      "  ,/,\n",
      "  and/CC\n",
      "  (NP execution/NN)\n",
      "  continues/VBZ\n",
      "  under/IN\n",
      "  (NP the/DT closing/NN)\n",
      "  (NP curly/JJ bracket/NN)\n",
      "  of/IN\n",
      "  (NP the/DT if-statement/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Note/NN)\n",
      "  that/IN\n",
      "  our/PRP$\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP method/NN)\n",
      "  (NP call/NN)\n",
      "  is/VBZ\n",
      "  outside/IN\n",
      "  the/DT\n",
      "  if-statement/JJ\n",
      "  ,/,\n",
      "  so/IN\n",
      "  it/PRP\n",
      "  will/MD\n",
      "  be/VB\n",
      "  executed/VBN\n",
      "  in/IN\n",
      "  (NP any/DT case/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  In/IN\n",
      "  other/JJ\n",
      "  words/NNS\n",
      "  :/:\n",
      "  If/IN\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  at/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  turn/VBP\n",
      "  and/CC\n",
      "  then/RB\n",
      "  move/VB\n",
      "  ;/:\n",
      "  if/IN\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  not/RB\n",
      "  at/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT world/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  just/RB\n",
      "  move/VB\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  can/MD\n",
      "  now/RB\n",
      "  combine/VB\n",
      "  (NP this/DT method/NN)\n",
      "  with/IN\n",
      "  an/DT\n",
      "  if-statement/JJ\n",
      "  to/TO\n",
      "  write/VB\n",
      "  (NP the/DT code/NN)\n",
      "  shown/VBN\n",
      "  in/IN\n",
      "  Code/NNP\n",
      "  2.3/CD\n",
      "  ./.)\n",
      "(S\n",
      "  2.5/CD\n",
      "  Summary/NNP\n",
      "  of/IN\n",
      "  programming/VBG\n",
      "  techniques/NNS\n",
      "  |/$\n",
      "  25/CD\n",
      "  Exercise/NNP\n",
      "  2.12/CD\n",
      "  Try/NNP\n",
      "  it/PRP\n",
      "  out/RP\n",
      "  !/.)\n",
      "(S\n",
      "  (NP Type/NN)\n",
      "  in/IN\n",
      "  (NP the/DT code/NN)\n",
      "  discussed/VBN\n",
      "  above/IN\n",
      "  and/CC\n",
      "  see/VB\n",
      "  if/IN\n",
      "  you/PRP\n",
      "  can/MD\n",
      "  make/VB\n",
      "  your/PRP$\n",
      "  (NP crabs/NN)\n",
      "  (NP turn/NN)\n",
      "  at/IN\n",
      "  (NP the/DT edge/NN)\n",
      "  of/IN\n",
      "  (NP the/DT screen/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Pay/NNP\n",
      "  (NP close/JJ attention/NN)\n",
      "  to/TO\n",
      "  (NP the/DT opening/NN)\n",
      "  and/CC\n",
      "  (NP closing/NN)\n",
      "  (NP brackets—it/NN)\n",
      "  is/VBZ\n",
      "  easy/JJ\n",
      "  to/TO\n",
      "  miss/VB\n",
      "  one/CD\n",
      "  or/CC\n",
      "  have/VB\n",
      "  too/RB\n",
      "  many/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.13/CD\n",
      "  (NP Experiment/NN)\n",
      "  with/IN\n",
      "  different/JJ\n",
      "  values/NNS\n",
      "  for/IN\n",
      "  (NP the/DT parameter/NN)\n",
      "  to/TO\n",
      "  (NP the/DT turn/NN)\n",
      "  (NP method/NN)\n",
      "  ./.)\n",
      "(S Find/VB (NP one/NN) that/WDT looks/VBZ good/JJ ./.)\n",
      "(S\n",
      "  (NP Exercise/NN)\n",
      "  2.14/CD\n",
      "  (NP Place/NN)\n",
      "  (NP the/DT move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  (NP statement/NN)\n",
      "  inside/IN\n",
      "  the/DT\n",
      "  if-statement/JJ\n",
      "  ,/,\n",
      "  rather/RB\n",
      "  than/IN\n",
      "  after/IN\n",
      "  it/PRP\n",
      "  ./.)\n",
      "(S\n",
      "  Find/VB\n",
      "  out/RP\n",
      "  what/WP\n",
      "  is/VBZ\n",
      "  (NP the/DT effect/NN)\n",
      "  and/CC\n",
      "  explain/VB\n",
      "  (NP the/DT behavior/NN)\n",
      "  you/PRP\n",
      "  observe/VBP\n",
      "  ./.)\n",
      "(S\n",
      "  (/(\n",
      "  Then/RB\n",
      "  ,/,\n",
      "  fix/VB\n",
      "  it/PRP\n",
      "  again/RB\n",
      "  by/IN\n",
      "  moving/VBG\n",
      "  it/PRP\n",
      "  back/RB\n",
      "  where/WRB\n",
      "  it/PRP\n",
      "  was/VBD\n",
      "  ./.\n",
      "  )/))\n",
      "(S\n",
      "  (NP Tip/NN)\n",
      "  :/:\n",
      "  In/IN\n",
      "  the/DT\n",
      "  Greenfoot/NNP\n",
      "  (NP editor/NN)\n",
      "  ,/,\n",
      "  when/WRB\n",
      "  you/PRP\n",
      "  place/VBP\n",
      "  (NP the/DT cursor/NN)\n",
      "  behind/IN\n",
      "  (NP an/DT opening/NN)\n",
      "  or/CC\n",
      "  (NP closing/NN)\n",
      "  (NP bracket/NN)\n",
      "  ,/,\n",
      "  Greenfoot/NNP\n",
      "  will/MD\n",
      "  mark/VB\n",
      "  the/DT\n",
      "  matching/VBG\n",
      "  (NP closing/NN)\n",
      "  or/CC\n",
      "  opening/VBG\n",
      "  (NP bracket/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  can/MD\n",
      "  be/VB\n",
      "  used/VBN\n",
      "  to/TO\n",
      "  check/VB\n",
      "  whether/IN\n",
      "  your/PRP$\n",
      "  brackets/NNS\n",
      "  match/VBP\n",
      "  up/RP\n",
      "  as/IN\n",
      "  they/PRP\n",
      "  should/MD\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Note/NN)\n",
      "  :/:\n",
      "  (NP Indentation/NN)\n",
      "  In/IN\n",
      "  all/PDT\n",
      "  (NP the/DT code/NN)\n",
      "  examples/VBZ\n",
      "  you/PRP\n",
      "  have/VBP\n",
      "  seen/VBN\n",
      "  so/RB\n",
      "  far/RB\n",
      "  (/(\n",
      "  for/IN\n",
      "  (NP instance/NN)\n",
      "  ,/,\n",
      "  Code/NNP\n",
      "  2.3/CD\n",
      "  )/)\n",
      "  ,/,\n",
      "  you/PRP\n",
      "  may/MD\n",
      "  have/VB\n",
      "  noticed/VBN\n",
      "  (NP some/DT careful/JJ indentation/NN)\n",
      "  being/VBG\n",
      "  used/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Every/DT time/NN)\n",
      "  (NP a/DT curly/JJ bracket/NN)\n",
      "  opens/NNS\n",
      "  ,/,\n",
      "  the/DT\n",
      "  following/JJ\n",
      "  lines/NNS\n",
      "  are/VBP\n",
      "  indented/JJ\n",
      "  one/CD\n",
      "  (NP level/NN)\n",
      "  more/JJR\n",
      "  than/IN\n",
      "  the/DT\n",
      "  previous/JJ\n",
      "  ones/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  When/WRB\n",
      "  a/DT\n",
      "  curly/RB\n",
      "  (NP bracket/NN)\n",
      "  closes/NNS\n",
      "  ,/,\n",
      "  (NP the/DT indentation/NN)\n",
      "  goes/VBZ\n",
      "  back/RB\n",
      "  one/CD\n",
      "  (NP level/NN)\n",
      "  ,/,\n",
      "  so/IN\n",
      "  that/IN\n",
      "  (NP the/DT closing/NN)\n",
      "  (NP curly/JJ bracket/NN)\n",
      "  is/VBZ\n",
      "  directly/RB\n",
      "  below/IN\n",
      "  the/DT\n",
      "  matching/VBG\n",
      "  (NP opening/NN)\n",
      "  (NP bracket/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  makes/VBZ\n",
      "  it/PRP\n",
      "  easy/JJ\n",
      "  to/TO\n",
      "  find/VB\n",
      "  (NP the/DT matching/NN)\n",
      "  (NP bracket/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  use/VBP\n",
      "  four/CD\n",
      "  spaces/NNS\n",
      "  for/IN\n",
      "  one/CD\n",
      "  (NP level/NN)\n",
      "  of/IN\n",
      "  (NP indentation/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  The/DT\n",
      "  Tab/NNP\n",
      "  (NP key/NN)\n",
      "  will/MD\n",
      "  insert/VB\n",
      "  spaces/NNS\n",
      "  in/IN\n",
      "  your/PRP$\n",
      "  (NP editor/NN)\n",
      "  for/IN\n",
      "  one/CD\n",
      "  (NP level/NN)\n",
      "  of/IN\n",
      "  (NP indentation/NN)\n",
      "  as/IN\n",
      "  well/RB\n",
      "  ./.)\n",
      "(S\n",
      "  Taking/VBG\n",
      "  (NP care/NN)\n",
      "  with/IN\n",
      "  (NP indentation/NN)\n",
      "  in/IN\n",
      "  your/PRP$\n",
      "  (NP own/JJ code/NN)\n",
      "  is/VBZ\n",
      "  very/RB\n",
      "  important/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  you/PRP\n",
      "  do/VBP\n",
      "  not/RB\n",
      "  indent/VB\n",
      "  carefully/RB\n",
      "  ,/,\n",
      "  some/DT\n",
      "  errors/NNS\n",
      "  (/(\n",
      "  particularly/RB\n",
      "  misplaced/VBN\n",
      "  or/CC\n",
      "  mismatched/VBN\n",
      "  curly/JJ\n",
      "  brackets/NNS\n",
      "  )/)\n",
      "  are/VBP\n",
      "  very/RB\n",
      "  hard/JJ\n",
      "  to/TO\n",
      "  spot/VB\n",
      "  ./.)\n",
      "(S\n",
      "  (NP Proper/JJ indentation/NN)\n",
      "  makes/VBZ\n",
      "  code/RB\n",
      "  much/JJ\n",
      "  easier/JJR\n",
      "  to/TO\n",
      "  read/VB\n",
      "  ,/,\n",
      "  and/CC\n",
      "  thus/RB\n",
      "  avoid/VB\n",
      "  potential/JJ\n",
      "  errors/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  2.5/CD\n",
      "  Summary/NNP\n",
      "  of/IN\n",
      "  programming/VBG\n",
      "  techniques/NNS\n",
      "  In/IN\n",
      "  (NP this/DT book/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  are/VBP\n",
      "  discussing/VBG\n",
      "  programming/VBG\n",
      "  from/IN\n",
      "  a/DT\n",
      "  very/RB\n",
      "  (NP example-driven/JJ perspective/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  introduce/VBP\n",
      "  (NP general/JJ programming/NN)\n",
      "  techniques/NNS\n",
      "  as/IN\n",
      "  we/PRP\n",
      "  need/VBP\n",
      "  them/PRP\n",
      "  to/TO\n",
      "  improve/VB\n",
      "  our/PRP$\n",
      "  scenarios/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  shall/MD\n",
      "  summarize/VB\n",
      "  (NP the/DT important/JJ programming/NN)\n",
      "  techniques/NNS\n",
      "  at/IN\n",
      "  (NP the/DT end/NN)\n",
      "  of/IN\n",
      "  (NP each/DT chapter/NN)\n",
      "  to/TO\n",
      "  make/VB\n",
      "  it/PRP\n",
      "  clear/JJ\n",
      "  what/WP\n",
      "  you/PRP\n",
      "  really/RB\n",
      "  need/VB\n",
      "  to/TO\n",
      "  take/VB\n",
      "  away/RP\n",
      "  from/IN\n",
      "  (NP the/DT discussion/NN)\n",
      "  in/IN\n",
      "  (NP order/NN)\n",
      "  to/TO\n",
      "  progress/VB\n",
      "  well/RB\n",
      "  ./.)\n",
      "(S\n",
      "  In/IN\n",
      "  (NP this/DT chapter/NN)\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  seen/VBN\n",
      "  how/WRB\n",
      "  to/TO\n",
      "  call/VB\n",
      "  methods/NNS\n",
      "  (/(\n",
      "  such/JJ\n",
      "  as/IN\n",
      "  (NP move/NN)\n",
      "  (/(\n",
      "  )/)\n",
      "  )/)\n",
      "  ,/,\n",
      "  with/IN\n",
      "  and/CC\n",
      "  without/IN\n",
      "  parameters/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  will/MD\n",
      "  form/VB\n",
      "  (NP the/DT basis/NN)\n",
      "  for/IN\n",
      "  all/DT\n",
      "  further/JJ\n",
      "  Java/NNP\n",
      "  (NP programming/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  have/VBP\n",
      "  also/RB\n",
      "  learnt/VBN\n",
      "  to/TO\n",
      "  identify/VB\n",
      "  (NP the/DT body/NN)\n",
      "  of/IN\n",
      "  (NP the/DT act/NN)\n",
      "  (NP method—this/NN)\n",
      "  is/VBZ\n",
      "  where/WRB\n",
      "  we/PRP\n",
      "  start/VBP\n",
      "  writing/VBG\n",
      "  our/PRP$\n",
      "  instructions/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  You/PRP\n",
      "  have/VBP\n",
      "  encountered/VBN\n",
      "  (NP some/DT error/NN)\n",
      "  messages/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  will/MD\n",
      "  continue/VB\n",
      "  throughout/IN\n",
      "  all/DT\n",
      "  your/PRP$\n",
      "  (NP programming/NN)\n",
      "  endeavors/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  all/DT\n",
      "  make/VBP\n",
      "  mistakes/NNS\n",
      "  ,/,\n",
      "  and/CC\n",
      "  we/PRP\n",
      "  all/DT\n",
      "  encounter/VBP\n",
      "  (NP error/NN)\n",
      "  messages/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  is/VBZ\n",
      "  not/RB\n",
      "  (NP a/DT sign/NN)\n",
      "  of/IN\n",
      "  (NP a/DT bad/JJ programmer—it/NN)\n",
      "  is/VBZ\n",
      "  (NP a/DT normal/JJ part/NN)\n",
      "  of/IN\n",
      "  (NP programming/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  We/PRP\n",
      "  have/VBP\n",
      "  encountered/VBN\n",
      "  (NP a/DT first/JJ glimpse/NN)\n",
      "  of/IN\n",
      "  (NP inheritance/NN)\n",
      "  :/:\n",
      "  Classes/NNS\n",
      "  inherit/VBP\n",
      "  the/DT\n",
      "  methods/NNS\n",
      "  from/IN\n",
      "  their/PRP$\n",
      "  superclasses/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  The/DT\n",
      "  Documentation/NNP\n",
      "  (NP view/NN)\n",
      "  of/IN\n",
      "  (NP a/DT class/NN)\n",
      "  gives/VBZ\n",
      "  us/PRP\n",
      "  (NP a/DT summary/NN)\n",
      "  of/IN\n",
      "  the/DT\n",
      "  methods/NNS\n",
      "  available/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  And/CC\n",
      "  ,/,\n",
      "  very/RB\n",
      "  importantly/RB\n",
      "  ,/,\n",
      "  we/PRP\n",
      "  have/VBP\n",
      "  seen/VBN\n",
      "  how/WRB\n",
      "  to/TO\n",
      "  make/VB\n",
      "  decisions/NNS\n",
      "  :/:\n",
      "  We/PRP\n",
      "  have/VBP\n",
      "  used/VBN\n",
      "  an/DT\n",
      "  if-statement/JJ\n",
      "  for/IN\n",
      "  (NP conditional/JJ execution/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  This/DT\n",
      "  went/VBD\n",
      "  (NP hand/NN)\n",
      "  in/IN\n",
      "  (NP hand/NN)\n",
      "  with/IN\n",
      "  (NP the/DT appearance/NN)\n",
      "  of/IN\n",
      "  (NP the/DT type/NN)\n",
      "  (NP boolean/NN)\n",
      "  ,/,\n",
      "  (NP a/DT value/NN)\n",
      "  that/WDT\n",
      "  can/MD\n",
      "  be/VB\n",
      "  true/JJ\n",
      "  or/CC\n",
      "  false/JJ\n",
      "  ./.)\n",
      "(S\n",
      "  26/CD\n",
      "  (NP |/JJ Chapter/NN)\n",
      "  2/CD\n",
      "  ■/IN\n",
      "  (NP The/DT first/JJ program/NN)\n",
      "  :/:\n",
      "  Little/JJ\n",
      "  Crab/NNP\n",
      "  Concept/NNP\n",
      "  summary/JJ\n",
      "  ■/VBD\n",
      "  (NP A/DT method/NN)\n",
      "  (NP call/NN)\n",
      "  is/VBZ\n",
      "  (NP an/DT instruction/NN)\n",
      "  that/WDT\n",
      "  tells/VBZ\n",
      "  (NP an/DT object/NN)\n",
      "  to/TO\n",
      "  perform/VB\n",
      "  (NP an/DT action/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT action/NN)\n",
      "  is/VBZ\n",
      "  defined/VBN\n",
      "  by/IN\n",
      "  (NP a/DT method/NN)\n",
      "  of/IN\n",
      "  (NP the/DT object/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  ■/JJ\n",
      "  Additional/NNP\n",
      "  (NP information/NN)\n",
      "  can/MD\n",
      "  be/VB\n",
      "  passed/VBN\n",
      "  to/TO\n",
      "  some/DT\n",
      "  methods/NNS\n",
      "  within/IN\n",
      "  the/DT\n",
      "  parentheses/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  (NP The/DT value/NN)\n",
      "  passed/VBN\n",
      "  is/VBZ\n",
      "  called/VBN\n",
      "  (NP a/DT parameter/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  ■/JJ\n",
      "  Multiple/NNP\n",
      "  instructions/NNS\n",
      "  are/VBP\n",
      "  executed/VBN\n",
      "  in/IN\n",
      "  (NP sequence/NN)\n",
      "  ,/,\n",
      "  one/CD\n",
      "  after/IN\n",
      "  the/DT\n",
      "  other/JJ\n",
      "  ,/,\n",
      "  in/IN\n",
      "  (NP the/DT order/NN)\n",
      "  in/IN\n",
      "  which/WDT\n",
      "  they/PRP\n",
      "  are/VBP\n",
      "  written/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  (NP ■/NN)\n",
      "  When/WRB\n",
      "  (NP a/DT class/NN)\n",
      "  is/VBZ\n",
      "  compiled/VBN\n",
      "  ,/,\n",
      "  (NP the/DT compiler/NN)\n",
      "  checks/NNS\n",
      "  to/TO\n",
      "  see/VB\n",
      "  whether/IN\n",
      "  there/EX\n",
      "  are/VBP\n",
      "  any/DT\n",
      "  errors/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  If/IN\n",
      "  (NP an/DT error/NN)\n",
      "  is/VBZ\n",
      "  found/VBN\n",
      "  ,/,\n",
      "  (NP an/DT error/NN)\n",
      "  (NP message/NN)\n",
      "  is/VBZ\n",
      "  displayed/VBN\n",
      "  ./.)\n",
      "(S\n",
      "  ■/VB\n",
      "  A/NNP\n",
      "  (NP subclass/NN)\n",
      "  inherits/VBZ\n",
      "  all/PDT\n",
      "  the/DT\n",
      "  methods/NNS\n",
      "  from/IN\n",
      "  its/PRP$\n",
      "  (NP superclass/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  That/DT\n",
      "  means/VBZ\n",
      "  that/IN\n",
      "  it/PRP\n",
      "  has/VBZ\n",
      "  ,/,\n",
      "  and/CC\n",
      "  can/MD\n",
      "  use/VB\n",
      "  ,/,\n",
      "  all/DT\n",
      "  methods/NNS\n",
      "  that/IN\n",
      "  its/PRP$\n",
      "  (NP superclass/NN)\n",
      "  defines/NNS\n",
      "  ./.)\n",
      "(S\n",
      "  (NP ■/NN)\n",
      "  Calling/VBG\n",
      "  (NP a/DT method/NN)\n",
      "  with/IN\n",
      "  (NP a/DT void/JJ return/NN)\n",
      "  (NP type/NN)\n",
      "  issues/NNS\n",
      "  (NP a/DT command/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  Calling/VBG\n",
      "  (NP a/DT method/NN)\n",
      "  with/IN\n",
      "  (NP a/DT non-void/JJ return/NN)\n",
      "  (NP type/NN)\n",
      "  asks/VBZ\n",
      "  (NP a/DT question/NN)\n",
      "  ./.)\n",
      "(S\n",
      "  ■/VB\n",
      "  An/DT\n",
      "  if-statement/JJ\n",
      "  can/MD\n",
      "  be/VB\n",
      "  used/VBN\n",
      "  to/TO\n",
      "  write/VB\n",
      "  instructions/NNS\n",
      "  that/WDT\n",
      "  are/VBP\n",
      "  executed/VBN\n",
      "  only/RB\n",
      "  when/WRB\n",
      "  (NP a/DT certain/JJ condition/NN)\n",
      "  is/VBZ\n",
      "  true/JJ\n",
      "  ./.)\n"
     ]
    }
   ],
   "source": [
    "grammar = \"NP: {<DT>?<JJ>*<NN>}\"\n",
    "cp = nltk.RegexpParser(grammar)\n",
    "for s in sentences:\n",
    "    result = cp.parse(s)\n",
    "    print(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "neResult = []\n",
    "for s in sentences:\n",
    "    neResult.append(nltk.ne_chunk(s,binary=False))\n",
    "    nltk.ne_chunk(s,binary=False).draw()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 94,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['program',\n",
       " 'topics',\n",
       " 'code',\n",
       " 'movement',\n",
       " 'screen',\n",
       " 'concepts',\n",
       " 'source',\n",
       " 'code',\n",
       " 'method',\n",
       " 'call',\n",
       " 'parameter',\n",
       " 'sequence',\n",
       " 'Exercise',\n",
       " 'Start',\n",
       " 'Greenfoot',\n",
       " 'scenario',\n",
       " 'crab',\n",
       " 'world',\n",
       " 'program',\n",
       " 'Run',\n",
       " 'button',\n",
       " 'Remember',\n",
       " 'class',\n",
       " 'icons',\n",
       " 'appear',\n",
       " 'project',\n",
       " 'right',\n",
       " 'classes',\n",
       " 'scenario',\n",
       " 'Figure',\n",
       " 'Greenfoot',\n",
       " 'Actor',\n",
       " 'class',\n",
       " 'class',\n",
       " 'Animal',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'hierarchy',\n",
       " 'arrows',\n",
       " 'relationship',\n",
       " 'inheritance',\n",
       " 'crab',\n",
       " 'animal',\n",
       " 'animal',\n",
       " 'actor',\n",
       " 'crab',\n",
       " 'actor',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'Actor',\n",
       " 'Animal',\n",
       " 'classes',\n",
       " 'exercise',\n",
       " 'answer',\n",
       " 'question',\n",
       " '“nothing”',\n",
       " 'Crab',\n",
       " 'scenario',\n",
       " 'Figure',\n",
       " 'Crab',\n",
       " 'scenario',\n",
       " 'Figure',\n",
       " 'Little',\n",
       " 'Crab',\n",
       " 'actor',\n",
       " 'crab',\n",
       " 'anything',\n",
       " 'Greenfoot',\n",
       " 'source',\n",
       " 'code',\n",
       " 'definition',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'chapter',\n",
       " 'thing',\n",
       " 'crab',\n",
       " 'move',\n",
       " 'crab',\n",
       " 'move',\n",
       " 'Let',\n",
       " 'look',\n",
       " 'source',\n",
       " 'code',\n",
       " 'class',\n",
       " 'Crab',\n",
       " 'editor',\n",
       " 'Crab',\n",
       " 'source',\n",
       " 'Open',\n",
       " 'editor',\n",
       " 'function',\n",
       " 'class’s',\n",
       " 'popup',\n",
       " 'menu',\n",
       " 'class',\n",
       " 'source',\n",
       " 'code',\n",
       " 'Code',\n",
       " 'Chapter',\n",
       " 'program',\n",
       " 'Crab',\n",
       " 'Code',\n",
       " 'version',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'import',\n",
       " 'greenfoot',\n",
       " '*',\n",
       " '//',\n",
       " 'World',\n",
       " 'Actor',\n",
       " 'GreenfootImage',\n",
       " 'Greenfoot',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'Crabs',\n",
       " 'beach',\n",
       " 'class',\n",
       " 'Crab',\n",
       " 'Animal',\n",
       " 'void',\n",
       " 'act',\n",
       " 'Add',\n",
       " 'action',\n",
       " 'code',\n",
       " 'here.',\n",
       " 'Java',\n",
       " 'class',\n",
       " 'definition',\n",
       " 'text',\n",
       " 'crab',\n",
       " 'detail',\n",
       " 'crab',\n",
       " 'class',\n",
       " 'definition',\n",
       " 'act',\n",
       " 'method',\n",
       " 'void',\n",
       " 'act',\n",
       " 'Add',\n",
       " 'action',\n",
       " 'code',\n",
       " 'here.',\n",
       " 'line',\n",
       " 'signature',\n",
       " 'method',\n",
       " 'brackets',\n",
       " 'anything',\n",
       " 'them—is',\n",
       " 'body',\n",
       " 'method',\n",
       " 'code',\n",
       " 'actions',\n",
       " 'crab',\n",
       " 'text',\n",
       " 'middle',\n",
       " 'command',\n",
       " 'command',\n",
       " 'move',\n",
       " 'parentheses',\n",
       " 'semicolon',\n",
       " 'act',\n",
       " 'method',\n",
       " 'void',\n",
       " 'act',\n",
       " 'move',\n",
       " 'Exercise',\n",
       " 'Change',\n",
       " 'act',\n",
       " 'method',\n",
       " 'crab',\n",
       " 'class',\n",
       " 'move',\n",
       " 'instruction',\n",
       " 'scenario',\n",
       " 'Compile',\n",
       " 'All',\n",
       " 'button',\n",
       " 'place',\n",
       " 'crab',\n",
       " 'world',\n",
       " 'Act',\n",
       " 'Run',\n",
       " 'buttons',\n",
       " 'Exercise',\n",
       " 'Place',\n",
       " 'crabs',\n",
       " 'world',\n",
       " 'scenario',\n",
       " 'Concept',\n",
       " 'method',\n",
       " 'call',\n",
       " 'instruction',\n",
       " 'object',\n",
       " 'action',\n",
       " 'action',\n",
       " 'method',\n",
       " 'object',\n",
       " 'crab',\n",
       " 'screen',\n",
       " 'move',\n",
       " 'instruction',\n",
       " 'move',\n",
       " 'bit',\n",
       " 'right',\n",
       " 'Act',\n",
       " 'button',\n",
       " 'Greenfoot',\n",
       " 'window',\n",
       " 'act',\n",
       " 'method',\n",
       " 'instruction',\n",
       " 'act',\n",
       " 'method',\n",
       " 'Run',\n",
       " 'button',\n",
       " 'Act',\n",
       " 'times',\n",
       " 'act',\n",
       " 'method',\n",
       " 'Pause',\n",
       " 'Terminology',\n",
       " 'instruction',\n",
       " 'move',\n",
       " 'method',\n",
       " 'call',\n",
       " 'method',\n",
       " 'action',\n",
       " 'object',\n",
       " 'object',\n",
       " 'crab',\n",
       " 'method',\n",
       " 'call',\n",
       " 'instruction',\n",
       " 'crab',\n",
       " 'parentheses',\n",
       " 'part',\n",
       " 'method',\n",
       " 'call',\n",
       " 'Instructions',\n",
       " 'end',\n",
       " 'semicolon',\n",
       " 'Concept',\n",
       " 'information',\n",
       " 'methods',\n",
       " 'parentheses',\n",
       " 'value',\n",
       " 'parameter',\n",
       " 'instructions',\n",
       " 'crab',\n",
       " 'turn',\n",
       " 'instruction',\n",
       " 'turn',\n",
       " 'number',\n",
       " 'instruction',\n",
       " 'crab',\n",
       " 'parameter',\n",
       " 'numbers',\n",
       " 'example',\n",
       " 'turn',\n",
       " 'degree',\n",
       " 'value',\n",
       " 'degrees',\n",
       " 'value',\n",
       " 'degrees',\n",
       " 'way',\n",
       " 'degrees',\n",
       " 'move',\n",
       " 'instruction',\n",
       " 'turn',\n",
       " 'instruction',\n",
       " 'act',\n",
       " 'method',\n",
       " 'void',\n",
       " 'act',\n",
       " 'turn',\n",
       " 'Exercise',\n",
       " 'Replace',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'scenario',\n",
       " 'values',\n",
       " 'Remember',\n",
       " 'time',\n",
       " 'source',\n",
       " 'code',\n",
       " 'Exercise',\n",
       " 'crab',\n",
       " 'turn',\n",
       " 'Concept',\n",
       " 'instructions',\n",
       " 'sequence',\n",
       " 'order',\n",
       " 'Chapter',\n",
       " 'program',\n",
       " 'Crab',\n",
       " 'Code',\n",
       " 'crab',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'import',\n",
       " 'greenfoot',\n",
       " '*',\n",
       " '//',\n",
       " 'World',\n",
       " 'Actor',\n",
       " 'GreenfootImage',\n",
       " 'Greenfoot',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'Crabs',\n",
       " 'beach',\n",
       " 'class',\n",
       " 'Crab',\n",
       " 'Animal',\n",
       " 'void',\n",
       " 'act',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'thing',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'act',\n",
       " 'method',\n",
       " 'instruction—we',\n",
       " 'instructions',\n",
       " 'row',\n",
       " 'Code',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'case',\n",
       " 'step',\n",
       " 'crab',\n",
       " 'actions',\n",
       " 'time',\n",
       " 'Exercise',\n",
       " 'Use',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'N',\n",
       " 'instruction',\n",
       " 'crab’s',\n",
       " 'act',\n",
       " 'method',\n",
       " 'values',\n",
       " 'N.',\n",
       " 'Terminology',\n",
       " 'number',\n",
       " 'parentheses',\n",
       " 'turn',\n",
       " 'instruction—that',\n",
       " 'turn',\n",
       " '—is',\n",
       " 'parameter',\n",
       " 'parameter',\n",
       " 'bit',\n",
       " 'information',\n",
       " 'methods',\n",
       " 'methods',\n",
       " 'move',\n",
       " 'parameters',\n",
       " 'move',\n",
       " 'instruction',\n",
       " 'methods',\n",
       " 'turn',\n",
       " 'information',\n",
       " 'case',\n",
       " 'information',\n",
       " 'form',\n",
       " 'parameter',\n",
       " 'value',\n",
       " 'parentheses',\n",
       " 'instance',\n",
       " 'turn',\n",
       " 'edges',\n",
       " 'Concept',\n",
       " 'class',\n",
       " 'compiler',\n",
       " 'checks',\n",
       " 'errors',\n",
       " 'error',\n",
       " 'error',\n",
       " 'message',\n",
       " 'note',\n",
       " 'Errors',\n",
       " 'source',\n",
       " 'code',\n",
       " 'character',\n",
       " 'counts',\n",
       " 'thing',\n",
       " 'program',\n",
       " 'programs',\n",
       " 'mistakes',\n",
       " 'example',\n",
       " 'semicolon',\n",
       " 'move',\n",
       " 'instruction',\n",
       " 'Exercise',\n",
       " 'Open',\n",
       " 'editor',\n",
       " 'crab’s',\n",
       " 'source',\n",
       " 'code',\n",
       " 'semicolon',\n",
       " 'move',\n",
       " 'compile',\n",
       " 'errors',\n",
       " 'move',\n",
       " 'changes',\n",
       " 'code',\n",
       " 'Make',\n",
       " 'exercise',\n",
       " 'Exercise',\n",
       " 'Make',\n",
       " 'changes',\n",
       " 'error',\n",
       " 'messages',\n",
       " 'Find',\n",
       " 'error',\n",
       " 'messages',\n",
       " 'Write',\n",
       " 'error',\n",
       " 'message',\n",
       " 'change',\n",
       " 'error',\n",
       " 'Tip',\n",
       " 'error',\n",
       " 'message',\n",
       " 'bottom',\n",
       " 'editor',\n",
       " 'window',\n",
       " 'question',\n",
       " 'mark',\n",
       " 'button',\n",
       " 'right',\n",
       " 'button',\n",
       " 'information',\n",
       " 'error',\n",
       " 'message',\n",
       " 'exercise',\n",
       " 'detail',\n",
       " 'Greenfoot',\n",
       " 'editor',\n",
       " 'line',\n",
       " 'message',\n",
       " 'bottom',\n",
       " 'editor',\n",
       " 'window',\n",
       " 'message',\n",
       " 'error',\n",
       " 'messages',\n",
       " 'accuracy',\n",
       " 'usefulness',\n",
       " 'problem',\n",
       " 'line',\n",
       " 'line',\n",
       " 'problem',\n",
       " 'line',\n",
       " 'problem',\n",
       " 'example',\n",
       " '“',\n",
       " 'message',\n",
       " 'semicolon',\n",
       " 'fact',\n",
       " 'line',\n",
       " 'line',\n",
       " 'messages',\n",
       " 'time',\n",
       " 'message',\n",
       " 'code',\n",
       " 'everything',\n",
       " 'edges',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'sections',\n",
       " 'edge',\n",
       " 'screen',\n",
       " 'Greenfoot',\n",
       " 'actors',\n",
       " 'world',\n",
       " 'edge',\n",
       " 'behavior',\n",
       " 'crab',\n",
       " 'world',\n",
       " 'edge',\n",
       " 'question',\n",
       " 'Chapter',\n",
       " 'program',\n",
       " 'Crab',\n",
       " 'Exercise',\n",
       " 'Open',\n",
       " 'editor',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'Documentation',\n",
       " 'view',\n",
       " 'list',\n",
       " 'methods',\n",
       " 'class',\n",
       " '“Method',\n",
       " 'Summary”',\n",
       " 'methods',\n",
       " 'class',\n",
       " 'Above',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'methods',\n",
       " 'method',\n",
       " 'goal',\n",
       " 'fact',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'methods',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'animal',\n",
       " 'arrow',\n",
       " 'Crab',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'diagram',\n",
       " 'animal',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'inheritance',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'abilities',\n",
       " 'methods',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'question',\n",
       " 'animals',\n",
       " 'editor',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'editor',\n",
       " 'views',\n",
       " 'source',\n",
       " 'code',\n",
       " 'Crab',\n",
       " 'class',\n",
       " 'documentation',\n",
       " 'view',\n",
       " 'selection',\n",
       " 'menu',\n",
       " 'right',\n",
       " 'corner',\n",
       " 'editor',\n",
       " 'window',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'Documentation',\n",
       " 'view',\n",
       " 'Figure',\n",
       " 'Method',\n",
       " 'View',\n",
       " 'switch',\n",
       " 'Figure',\n",
       " 'Documentation',\n",
       " 'view',\n",
       " 'method',\n",
       " 'summary',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'Concept',\n",
       " 'subclass',\n",
       " 'methods',\n",
       " 'superclass',\n",
       " 'methods',\n",
       " 'superclass',\n",
       " 'defines',\n",
       " 'edges',\n",
       " 'method',\n",
       " 'summary',\n",
       " 'methods',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'methods',\n",
       " 'moment',\n",
       " 'atWorldEdge',\n",
       " 'edges',\n",
       " 'world',\n",
       " 'move',\n",
       " 'Move',\n",
       " 'direction',\n",
       " 'turn',\n",
       " 'angle',\n",
       " 'Turn',\n",
       " '“angle”',\n",
       " 'right',\n",
       " 'clockwise',\n",
       " 'signatures',\n",
       " 'methods',\n",
       " 'Chapter',\n",
       " 'method',\n",
       " 'signature',\n",
       " 'return',\n",
       " 'type',\n",
       " 'method',\n",
       " 'name',\n",
       " 'parameter',\n",
       " 'list',\n",
       " 'comment',\n",
       " 'method',\n",
       " 'method',\n",
       " 'names',\n",
       " 'atWorldEdge',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'methods',\n",
       " 'ones',\n",
       " 'sections',\n",
       " 'parameter',\n",
       " 'lists',\n",
       " 'move',\n",
       " 'parameters',\n",
       " 'parentheses',\n",
       " 'parameter',\n",
       " 'type',\n",
       " 'int',\n",
       " 'number',\n",
       " 'angle',\n",
       " 'Section',\n",
       " 'parameter',\n",
       " 'lists',\n",
       " 'move',\n",
       " 'turn',\n",
       " 'methods',\n",
       " 'return',\n",
       " 'type',\n",
       " 'method',\n",
       " 'value',\n",
       " 'object',\n",
       " 'animal',\n",
       " 'command',\n",
       " 'answer',\n",
       " 'signature',\n",
       " 'atWorldEdge',\n",
       " 'atWorldEdge',\n",
       " 'method',\n",
       " 'parameters',\n",
       " 'nothing',\n",
       " 'parentheses',\n",
       " 'return',\n",
       " 'value',\n",
       " 'boolean',\n",
       " 'type',\n",
       " 'Section',\n",
       " 'type',\n",
       " 'values',\n",
       " 'methods',\n",
       " 'values',\n",
       " 'return',\n",
       " 'type',\n",
       " 'command',\n",
       " 'question',\n",
       " 'atWorldEdge',\n",
       " 'method',\n",
       " 'method',\n",
       " 'method',\n",
       " 'edge',\n",
       " 'world',\n",
       " 'Exercise',\n",
       " 'Create',\n",
       " 'crab',\n",
       " 'atWorldEdge',\n",
       " 'method',\n",
       " 'Animal',\n",
       " 'submenu',\n",
       " 'crab',\n",
       " 'method',\n",
       " 'Animal',\n",
       " 'class',\n",
       " 'method',\n",
       " 'Exercise',\n",
       " 'Let',\n",
       " 'crab',\n",
       " 'run',\n",
       " 'edge',\n",
       " 'screen',\n",
       " 'atWorldEdge',\n",
       " 'method',\n",
       " 'Concept',\n",
       " 'method',\n",
       " 'return',\n",
       " 'type',\n",
       " 'issues',\n",
       " 'command',\n",
       " 'method',\n",
       " 'return',\n",
       " 'type',\n",
       " 'question',\n",
       " 'Concept',\n",
       " 'instructions',\n",
       " 'condition',\n",
       " 'Chapter',\n",
       " 'program',\n",
       " 'Crab',\n",
       " 'Code',\n",
       " 'edge',\n",
       " 'world',\n",
       " 'import',\n",
       " 'greenfoot',\n",
       " '*',\n",
       " '//',\n",
       " 'World',\n",
       " 'Actor',\n",
       " 'GreenfootImage',\n",
       " 'Greenfoot',\n",
       " 'class',\n",
       " 'crab',\n",
       " 'Crabs',\n",
       " 'beach',\n",
       " 'class',\n",
       " 'Crab',\n",
       " 'Animal',\n",
       " 'void',\n",
       " 'act',\n",
       " 'atWorldEdge',\n",
       " 'turn',\n",
       " 'part',\n",
       " 'Java',\n",
       " 'language',\n",
       " 'commands',\n",
       " 'condition',\n",
       " 'example',\n",
       " 'edge',\n",
       " 'world',\n",
       " 'code',\n",
       " 'atWorldEdge',\n",
       " 'turn',\n",
       " 'form',\n",
       " 'if-statement',\n",
       " 'condition',\n",
       " 'instruction',\n",
       " 'instruction',\n",
       " 'place',\n",
       " 'condition',\n",
       " 'expression',\n",
       " 'atWorldEdge',\n",
       " 'call',\n",
       " 'instructions',\n",
       " 'condition',\n",
       " 'instructions',\n",
       " 'condition',\n",
       " 'instructions',\n",
       " 'execution',\n",
       " 'closing',\n",
       " 'bracket',\n",
       " 'Note',\n",
       " 'move',\n",
       " 'method',\n",
       " 'call',\n",
       " 'case',\n",
       " 'words',\n",
       " 'edge',\n",
       " 'world',\n",
       " 'edge',\n",
       " 'world',\n",
       " 'method',\n",
       " 'code',\n",
       " 'Code',\n",
       " 'Summary',\n",
       " 'techniques',\n",
       " 'Exercise',\n",
       " 'Try',\n",
       " 'Type',\n",
       " 'code',\n",
       " 'crabs',\n",
       " 'turn',\n",
       " 'edge',\n",
       " 'screen',\n",
       " 'Pay',\n",
       " 'attention',\n",
       " 'opening',\n",
       " 'closing',\n",
       " 'brackets—it',\n",
       " 'Exercise',\n",
       " 'Experiment',\n",
       " 'values',\n",
       " 'parameter',\n",
       " 'turn',\n",
       " 'method',\n",
       " 'one',\n",
       " 'Exercise',\n",
       " 'Place',\n",
       " 'move',\n",
       " 'statement',\n",
       " 'effect',\n",
       " 'behavior',\n",
       " 'Tip',\n",
       " 'Greenfoot',\n",
       " 'editor',\n",
       " 'cursor',\n",
       " 'opening',\n",
       " 'closing',\n",
       " 'bracket',\n",
       " 'Greenfoot',\n",
       " 'closing',\n",
       " 'bracket',\n",
       " 'brackets',\n",
       " 'Indentation',\n",
       " 'code',\n",
       " 'instance',\n",
       " 'Code',\n",
       " 'indentation',\n",
       " 'time',\n",
       " 'bracket',\n",
       " 'opens',\n",
       " 'lines',\n",
       " 'level',\n",
       " 'ones',\n",
       " 'bracket',\n",
       " 'closes',\n",
       " 'indentation',\n",
       " 'level',\n",
       " 'closing',\n",
       " 'bracket',\n",
       " 'opening',\n",
       " 'bracket',\n",
       " 'matching',\n",
       " 'bracket',\n",
       " 'spaces',\n",
       " 'level',\n",
       " 'indentation',\n",
       " 'Tab',\n",
       " 'key',\n",
       " 'spaces',\n",
       " 'editor',\n",
       " 'level',\n",
       " 'indentation',\n",
       " 'care',\n",
       " 'indentation',\n",
       " 'code',\n",
       " 'errors',\n",
       " 'brackets',\n",
       " 'indentation',\n",
       " 'errors',\n",
       " 'Summary',\n",
       " 'techniques',\n",
       " 'book',\n",
       " 'perspective',\n",
       " 'programming',\n",
       " 'techniques',\n",
       " 'scenarios',\n",
       " 'programming',\n",
       " 'techniques',\n",
       " 'end',\n",
       " 'chapter',\n",
       " 'discussion',\n",
       " 'order',\n",
       " 'chapter',\n",
       " 'methods',\n",
       " 'move',\n",
       " 'parameters',\n",
       " 'basis',\n",
       " 'Java',\n",
       " 'programming',\n",
       " 'body',\n",
       " 'act',\n",
       " 'method—this',\n",
       " 'instructions',\n",
       " 'error',\n",
       " 'messages',\n",
       " 'programming',\n",
       " 'endeavors',\n",
       " 'mistakes',\n",
       " 'error',\n",
       " 'messages',\n",
       " 'sign',\n",
       " 'programmer—it',\n",
       " 'part',\n",
       " 'glimpse',\n",
       " 'inheritance',\n",
       " 'Classes',\n",
       " 'methods',\n",
       " 'superclasses',\n",
       " 'Documentation',\n",
       " 'view',\n",
       " 'class',\n",
       " 'summary',\n",
       " 'methods',\n",
       " 'decisions',\n",
       " 'execution',\n",
       " 'hand',\n",
       " 'hand',\n",
       " 'appearance',\n",
       " 'type',\n",
       " 'boolean',\n",
       " 'value',\n",
       " 'Chapter',\n",
       " 'program',\n",
       " 'Crab',\n",
       " 'Concept',\n",
       " 'method',\n",
       " 'call',\n",
       " 'instruction',\n",
       " 'object',\n",
       " 'action',\n",
       " 'action',\n",
       " 'method',\n",
       " 'object',\n",
       " 'information',\n",
       " 'methods',\n",
       " 'parentheses',\n",
       " 'value',\n",
       " 'parameter',\n",
       " 'instructions',\n",
       " 'sequence',\n",
       " 'order',\n",
       " 'class',\n",
       " 'compiler',\n",
       " 'checks',\n",
       " 'errors',\n",
       " 'error',\n",
       " 'error',\n",
       " 'message',\n",
       " 'subclass',\n",
       " 'methods',\n",
       " 'superclass',\n",
       " 'methods',\n",
       " 'superclass',\n",
       " 'defines',\n",
       " 'method',\n",
       " 'return',\n",
       " 'type',\n",
       " 'issues',\n",
       " 'command',\n",
       " 'method',\n",
       " 'return',\n",
       " 'type',\n",
       " 'question',\n",
       " 'instructions',\n",
       " 'condition']"
      ]
     },
     "execution_count": 94,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "is_noun = lambda pos: pos[:2] == 'NN'\n",
    "\n",
    "nouns = [word for (word, pos) in nltk.pos_tag(nltk.word_tokenize(data)) if is_noun(pos)] \n",
    "nouns"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": 89,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "194.4"
      ]
     },
     "execution_count": 89,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "0.9*len(sentences)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 90,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "train = sentences[:int(0.9*len(sentences))]\n",
    "test = sentences[int(0.9*len(sentences)):]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 91,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.827893175074184"
      ]
     },
     "execution_count": 91,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "tagger = UnigramTagger(train)\n",
    "tagger.evaluate(test)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 92,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.22255192878338279"
      ]
     },
     "execution_count": 92,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "tagger = BigramTagger(train)\n",
    "tagger.evaluate(test)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "###### Regex:\n",
    "r =  ved ikke                           \n",
    "' = start på string                                                                          \n",
    ". = any character, except for a new line\n",
    "* = match 0 or MORE repetitions                              \n",
    "\\b = space around whole words                                                                     \n",
    "in = part of sentence                                                                    \n",
    "\\b = space around whole words                                                                    \n",
    "( = part of sentence                                                                    \n",
    "? = match 0 or 1 repetitions.                                                                    \n",
    "! = donno prob part of sentence                                                                    \n",
    "\\b = space around whole words                                                                    \n",
    ". = any character, except for a new line                                                                      \n",
    "+ = match 1 or more repetitions                                                                    \n",
    "ing = part of sentence                                                                    \n",
    ") = part of sentence                                                                    \n",
    "' = end of string                                                                    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 95,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "ename": "ValueError",
     "evalue": "your value for the subject type has not been recognized: DT",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mValueError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-95-db8909d3361d>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      2\u001b[0m \u001b[0mIN\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mre\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mcompile\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34mr'.*\\bin\\b(?!\\b.+ing)'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 3\u001b[1;33m \u001b[1;32mfor\u001b[0m \u001b[0mrel\u001b[0m \u001b[1;32min\u001b[0m \u001b[0mnltk\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0msem\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mextract_rels\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34m'DT'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'NN'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0msentences\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mpattern\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mIN\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      4\u001b[0m     \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mnltk\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0msem\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mrtuple\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mrel\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
      "\u001b[1;32mC:\\Users\\Martin\\Anaconda3\\lib\\site-packages\\nltk\\sem\\relextract.py\u001b[0m in \u001b[0;36mextract_rels\u001b[1;34m(subjclass, objclass, doc, corpus, pattern, window)\u001b[0m\n\u001b[0;32m    204\u001b[0m             \u001b[0msubjclass\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0m_expand\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0msubjclass\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    205\u001b[0m         \u001b[1;32melse\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m--> 206\u001b[1;33m             \u001b[1;32mraise\u001b[0m \u001b[0mValueError\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34m\"your value for the subject type has not been recognized: %s\"\u001b[0m \u001b[1;33m%\u001b[0m \u001b[0msubjclass\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m    207\u001b[0m     \u001b[1;32mif\u001b[0m \u001b[0mobjclass\u001b[0m \u001b[1;32mand\u001b[0m \u001b[0mobjclass\u001b[0m \u001b[1;32mnot\u001b[0m \u001b[1;32min\u001b[0m \u001b[0mNE_CLASSES\u001b[0m\u001b[1;33m[\u001b[0m\u001b[0mcorpus\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m    208\u001b[0m         \u001b[1;32mif\u001b[0m \u001b[0m_expand\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mobjclass\u001b[0m\u001b[1;33m)\u001b[0m \u001b[1;32min\u001b[0m \u001b[0mNE_CLASSES\u001b[0m\u001b[1;33m[\u001b[0m\u001b[0mcorpus\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
      "\u001b[1;31mValueError\u001b[0m: your value for the subject type has not been recognized: DT"
     ]
    }
   ],
   "source": [
    "\n",
    "IN = re.compile(r'.*\\bin\\b(?!\\b.+ing)')\n",
    "for rel in nltk.sem.extract_rels('DT', 'NN', sentences, pattern = IN):\n",
    "    print(nltk.sem.rtuple(rel))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 96,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[ORG: 'WHYY'] 'in' [LOC: 'Philadelphia']\n",
      "[ORG: 'McGlashan &AMP; Sarrail'] 'firm in' [LOC: 'San Mateo']\n",
      "[ORG: 'Freedom Forum'] 'in' [LOC: 'Arlington']\n",
      "[ORG: 'Brookings Institution'] ', the research group in' [LOC: 'Washington']\n",
      "[ORG: 'Idealab'] ', a self-described business incubator based in' [LOC: 'Los Angeles']\n",
      "[ORG: 'Open Text'] ', based in' [LOC: 'Waterloo']\n",
      "[ORG: 'WGBH'] 'in' [LOC: 'Boston']\n",
      "[ORG: 'Bastille Opera'] 'in' [LOC: 'Paris']\n",
      "[ORG: 'Omnicom'] 'in' [LOC: 'New York']\n",
      "[ORG: 'DDB Needham'] 'in' [LOC: 'New York']\n",
      "[ORG: 'Kaplan Thaler Group'] 'in' [LOC: 'New York']\n",
      "[ORG: 'BBDO South'] 'in' [LOC: 'Atlanta']\n",
      "[ORG: 'Georgia-Pacific'] 'in' [LOC: 'Atlanta']\n"
     ]
    }
   ],
   "source": [
    "IN = re.compile(r'.*\\bin\\b(?!\\b.+ing)')\n",
    "for doc in nltk.corpus.ieer.parsed_docs('NYT_19980315'):\n",
    "    for rel in nltk.sem.extract_rels('ORG', 'LOC', doc,\n",
    "                                      corpus='ieer', pattern = IN):\n",
    "        print(nltk.sem.rtuple(rel))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 99,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<IEERDocument NYT19980315.0063: 'PUBLIC RADIO HOSTS DROP IN AND MAYBE STAY TOO LONG'>\n",
      "<IEERDocument NYT19980315.0064: 'IN CYBERSPACE, IS THERE LAW WHERE THERE IS NO LAND?'>\n",
      "<IEERDocument NYT19980315.0067: 'THE SITES: TUNING INTO MUSIC ON THE WEB'>\n",
      "<IEERDocument NYT19980315.0069: 'ANALYSIS: TAXING INTERNET SALES _ GOVERNORS VS. TAX FREEDOM ACT'>\n",
      "<IEERDocument NYT19980315.0070: 'A SEARCH ENGINE THAT CHARGES FOR TOP BILLING'>\n",
      "<IEERDocument NYT19980315.0071: 'COMING SOON: TV DOCUMENTARIES TO A BOOKSTORE NEAR YOU'>\n",
      "<IEERDocument NYT19980315.0072: 'WEATHER'>\n",
      "<IEERDocument NYT19980315.0073: 'DICAPRIO , CHARISMATIC STAR, BALKS AT TEEN IDOL IMAGE'>\n",
      "<IEERDocument NYT19980315.0074: \"You've read the book? Now see the television program. Inspired by ``Angela's...\">\n",
      "<IEERDocument NYT19980315.0084: 'A DIRECTOR WHO DARES, AND TAKES THE HEAT'>\n",
      "<IEERDocument NYT19980315.0085: 'ADVERTISING: AFTER 32 YEARS , WELLS BDDP WILL CLOSE'>\n",
      "<IEERDocument NYT19980315.0086: \"`THE GIFTS OF THE JEWS': DESERT NOMADS CHANGED THE WORLD WITH THE\">\n",
      "<IEERDocument NYT19980315.0087: 'MUSICIANS ON BROADWAY TO VOTE ON A CONTRACT'>\n"
     ]
    }
   ],
   "source": [
    "for doc in nltk.corpus.ieer.parsed_docs('NYT_19980315'):\n",
    "    print(doc)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 100,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[<IEERDocument NYT19980315.0063: 'PUBLIC RADIO HOSTS DROP IN AND MAYBE STAY TOO LONG'>, <IEERDocument NYT19980315.0064: 'IN CYBERSPACE, IS THERE LAW WHERE THERE IS NO LAND?'>, ...]\n"
     ]
    }
   ],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
 ],
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