diff --git a/README.md b/README.md
index a1d99f0..1e7ad37 100644
--- a/README.md
+++ b/README.md
@@ -37,11 +37,10 @@ Thanks to all [contributors](CONTRIBUTORS.txt).
 
 ```python
 from pyswip import Prolog
-prolog = Prolog()
-prolog.assertz("father(michael,john)")
-prolog.assertz("father(michael,gina)")
-list(prolog.query("father(michael,X)")) == [{'X': 'john'}, {'X': 'gina'}]
-for soln in prolog.query("father(X,Y)"):
+Prolog.assertz("father(michael,john)")
+Prolog.assertz("father(michael,gina)")
+list(Prolog.query("father(michael,X)")) == [{'X': 'john'}, {'X': 'gina'}]
+for soln in Prolog.query("father(X,Y)"):
     print(soln["X"], "is the father of", soln["Y"])
 # michael is the father of john
 # michael is the father of gina
@@ -52,8 +51,7 @@ Assuming the filename "knowledge_base.pl" and the Python is being run in the sam
 
 ```python
 from pyswip import Prolog
-prolog = Prolog()
-prolog.consult("knowledge_base.pl")
+Prolog.consult("knowledge_base.pl")
 ```
 
 ### Foreign Functions
@@ -67,10 +65,9 @@ hello.arity = 1
 
 registerForeign(hello)
 
-prolog = Prolog()
-prolog.assertz("father(michael,john)")
-prolog.assertz("father(michael,gina)")
-print(list(prolog.query("father(michael,X), hello(X)")))
+Prolog.assertz("father(michael,john)")
+Prolog.assertz("father(michael,gina)")
+print(list(Prolog.query("father(michael,X), hello(X)")))
 ```
 
 ### Pythonic interface (Experimental)
diff --git a/examples/README.md b/examples/README.md
index 39e3381..2dbd50d 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -7,7 +7,7 @@ The ones marked with (clp) requires `clp` library of SWI-Prolog.
 * (clp) `coins/`
 * (clp) `draughts/`
 * `hanoi/` : Towers of Hanoi
-* (clp) `sendmoremoney/` : if, SEND * MORE = MONEY, what is S, E, N, D, M, O, R, Y?
-* (clp) `sudoku/` : Sudoku solver (Prolog code is contributed by Markus Triska)
-* `create_term.py` : shows creating a Prolog term
-* `register_foreign.py` : shows registering a foreign function
+* (clp) `sendmoremoney/` : If, SEND * MORE = MONEY, what is S, E, N, D, M, O, R, Y?
+* (clp) `sudoku/` : Moved to `pyswip.examples.sudoku` package 
+* `create_term.py` : Shows creating a Prolog term
+* `register_foreign.py` : Shows registering a foreign function
diff --git a/examples/coins/coins.py b/examples/coins/coins.py
index a1ae124..3061ff2 100644
--- a/examples/coins/coins.py
+++ b/examples/coins/coins.py
@@ -25,17 +25,16 @@
 
 
 def main():
-    prolog = Prolog()
-    prolog.consult("coins.pl", relative_to=__file__)
+    Prolog.consult("coins.pl", relative_to=__file__)
     count = int(input("How many coins (default: 100)? ") or 100)
     total = int(input("What should be the total (default: 500)? ") or 500)
-    for i, soln in enumerate(prolog.query("coins(S, %d, %d)." % (count, total))):
+    for i, soln in enumerate(Prolog.query("coins(S, %d, %d)." % (count, total))):
         S = zip(soln["S"], [1, 5, 10, 50, 100])
         print(i, end=" ")
         for c, v in S:
             print(f"{c}x{v}", end=" ")
         print()
-    list(prolog.query(f"coins(S, {count}, {total})."))
+    list(Prolog.query(f"coins(S, {count}, {total})."))
 
 
 if __name__ == "__main__":
diff --git a/examples/coins/coins_new.py b/examples/coins/coins_new.py
index e12f08b..a435c52 100644
--- a/examples/coins/coins_new.py
+++ b/examples/coins/coins_new.py
@@ -25,8 +25,7 @@
 
 
 def main():
-    prolog = Prolog()
-    prolog.consult("coins.pl", relative_to=__file__)
+    Prolog.consult("coins.pl", relative_to=__file__)
     count = int(input("How many coins (default: 100)? ") or 100)
     total = int(input("What should be the total (default: 500)? ") or 500)
     coins = Functor("coins", 3)
diff --git a/examples/create_term.py b/examples/create_term.py
index 8bb33f0..0ff0135 100644
--- a/examples/create_term.py
+++ b/examples/create_term.py
@@ -26,8 +26,6 @@
 
 
 def main():
-    prolog = Prolog()
-
     a1 = PL_new_term_refs(2)
     a2 = a1 + 1
     t = PL_new_term_ref()
@@ -42,7 +40,7 @@ def main():
     PL_cons_functor_v(ta, assertz, t)
     PL_call(ta, None)
 
-    print(list(prolog.query("animal(X,Y)", catcherrors=True)))
+    print(list(Prolog.query("animal(X,Y)", catcherrors=True)))
 
 
 if __name__ == "__main__":
diff --git a/examples/draughts/puzzle1.py b/examples/draughts/puzzle1.py
index e44bfcb..e5345b1 100644
--- a/examples/draughts/puzzle1.py
+++ b/examples/draughts/puzzle1.py
@@ -37,10 +37,9 @@
 
 
 def main():
-    prolog = Prolog()
-    prolog.consult("puzzle1.pl", relative_to=__file__)
+    Prolog.consult("puzzle1.pl", relative_to=__file__)
 
-    for soln in prolog.query("solve(B)."):
+    for soln in Prolog.query("solve(B)."):
         B = soln["B"]
 
         # [NW,N,NE,W,E,SW,S,SE]
diff --git a/examples/father.py b/examples/father.py
index 655b5c0..6d8ecdb 100644
--- a/examples/father.py
+++ b/examples/father.py
@@ -21,19 +21,16 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-from __future__ import print_function
 from pyswip import *
 
 
 def main():
-    p = Prolog()
-
     father = Functor("father", 2)
     mother = Functor("mother", 2)
 
-    p.assertz("father(john,mich)")
-    p.assertz("father(john,gina)")
-    p.assertz("mother(jane,mich)")
+    Prolog.assertz("father(john,mich)")
+    Prolog.assertz("father(john,gina)")
+    Prolog.assertz("mother(jane,mich)")
 
     Y = Variable()
     Z = Variable()
@@ -47,7 +44,7 @@ def main():
     q.closeQuery()  # Newer versions of SWI-Prolog do not allow nested queries
 
     print("\nQuery with strings\n")
-    for s in p.query("father(john,Y),mother(Z,Y)"):
+    for s in Prolog.query("father(john,Y),mother(Z,Y)"):
         print(s["Y"], s["Z"])
 
 
diff --git a/examples/hanoi/hanoi.py b/examples/hanoi/hanoi.py
index 528a260..8d93563 100644
--- a/examples/hanoi/hanoi.py
+++ b/examples/hanoi/hanoi.py
@@ -76,12 +76,11 @@ def draw(self):
 
 def main():
     n = 3
-    prolog = Prolog()
     tower = Tower(n, True)
     notifier = Notifier(tower.move)
     registerForeign(notifier.notify)
-    prolog.consult("hanoi.pl", relative_to=__file__)
-    list(prolog.query("hanoi(%d)" % n))
+    Prolog.consult("hanoi.pl", relative_to=__file__)
+    list(Prolog.query("hanoi(%d)" % n))
 
 
 if __name__ == "__main__":
diff --git a/examples/hanoi/hanoi_simple.py b/examples/hanoi/hanoi_simple.py
index 0fb72ca..b7d9014 100644
--- a/examples/hanoi/hanoi_simple.py
+++ b/examples/hanoi/hanoi_simple.py
@@ -31,10 +31,9 @@ def notify(t):
 
     notify.arity = 1
 
-    prolog = Prolog()
     registerForeign(notify)
-    prolog.consult("hanoi.pl", relative_to=__file__)
-    list(prolog.query(f"hanoi({N})"))
+    Prolog.consult("hanoi.pl", relative_to=__file__)
+    list(Prolog.query(f"hanoi({N})"))
 
 
 if __name__ == "__main__":
diff --git a/examples/register_foreign.py b/examples/register_foreign.py
index cd7ad20..ca69214 100644
--- a/examples/register_foreign.py
+++ b/examples/register_foreign.py
@@ -33,6 +33,5 @@ def atom_checksum(*a):
         return False
 
 
-p = Prolog()
 registerForeign(atom_checksum, arity=2)
-print(list(p.query("X='Python', atom_checksum(X, Y)", catcherrors=False)))
+print(list(Prolog.query("X='Python', atom_checksum(X, Y)", catcherrors=False)))
diff --git a/examples/register_foreign_simple.py b/examples/register_foreign_simple.py
index edb818e..1c5c8ad 100644
--- a/examples/register_foreign_simple.py
+++ b/examples/register_foreign_simple.py
@@ -23,7 +23,6 @@
 
 # Demonstrates registering a Python function as a Prolog predicate through SWI-Prolog's FFI.
 
-from __future__ import print_function
 from pyswip.prolog import Prolog
 from pyswip.easy import registerForeign
 
@@ -37,10 +36,9 @@ def hello(t):
 
 def main():
     registerForeign(hello)
-    prolog = Prolog()
-    prolog.assertz("father(michael,john)")
-    prolog.assertz("father(michael,gina)")
-    list(prolog.query("father(michael,X), hello(X)"))
+    Prolog.assertz("father(michael,john)")
+    Prolog.assertz("father(michael,gina)")
+    list(Prolog.query("father(michael,X), hello(X)"))
 
 
 if __name__ == "__main__":
diff --git a/examples/sendmoremoney/money.py b/examples/sendmoremoney/money.py
index 21a4d2d..b2edfca 100644
--- a/examples/sendmoremoney/money.py
+++ b/examples/sendmoremoney/money.py
@@ -30,9 +30,8 @@
 from pyswip import Prolog
 
 letters = list("SENDMORY")
-prolog = Prolog()
-prolog.consult("money.pl", relative_to=__file__)
-for result in prolog.query("sendmore(X)"):
+Prolog.consult("money.pl", relative_to=__file__)
+for result in Prolog.query("sendmore(X)"):
     r = result["X"]
     for i, letter in enumerate(letters):
         print(letter, "=", r[i])
diff --git a/examples/sendmoremoney/money_new.py b/examples/sendmoremoney/money_new.py
index fcbc7a4..956c3ea 100644
--- a/examples/sendmoremoney/money_new.py
+++ b/examples/sendmoremoney/money_new.py
@@ -32,9 +32,8 @@
 
 def main():
     letters = list("SENDMORY")
-    prolog = Prolog()
     sendmore = Functor("sendmore")
-    prolog.consult("money.pl", relative_to=__file__)
+    Prolog.consult("money.pl", relative_to=__file__)
 
     X = Variable()
     call(sendmore(X))
diff --git a/examples/sudoku/sudoku.py b/examples/sudoku/sudoku.py
deleted file mode 100644
index 7108bfa..0000000
--- a/examples/sudoku/sudoku.py
+++ /dev/null
@@ -1,89 +0,0 @@
-# -*- coding: utf-8 -*-
-
-# pyswip -- Python SWI-Prolog bridge
-# Copyright (c) 2007-2018 Yüce Tekol
-#
-# Permission is hereby granted, free of charge, to any person obtaining a copy
-# of this software and associated documentation files (the "Software"), to deal
-# in the Software without restriction, including without limitation the rights
-# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-# copies of the Software, and to permit persons to whom the Software is
-# furnished to do so, subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be included in all
-# copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-# SOFTWARE.
-
-from __future__ import print_function
-from pyswip.prolog import Prolog
-from pyswip.easy import *
-
-
-_ = 0
-puzzle1 = [
-    [_, 6, _, 1, _, 4, _, 5, _],
-    [_, _, 8, 3, _, 5, 6, _, _],
-    [2, _, _, _, _, _, _, _, 1],
-    [8, _, _, 4, _, 7, _, _, 6],
-    [_, _, 6, _, _, _, 3, _, _],
-    [7, _, _, 9, _, 1, _, _, 4],
-    [5, _, _, _, _, _, _, _, 2],
-    [_, _, 7, 2, _, 6, 9, _, _],
-    [_, 4, _, 5, _, 8, _, 7, _],
-]
-
-
-puzzle2 = [
-    [_, _, 1, _, 8, _, 6, _, 4],
-    [_, 3, 7, 6, _, _, _, _, _],
-    [5, _, _, _, _, _, _, _, _],
-    [_, _, _, _, _, 5, _, _, _],
-    [_, _, 6, _, 1, _, 8, _, _],
-    [_, _, _, 4, _, _, _, _, _],
-    [_, _, _, _, _, _, _, _, 3],
-    [_, _, _, _, _, 7, 5, 2, _],
-    [8, _, 2, _, 9, _, 7, _, _],
-]
-
-
-def pretty_print(table):
-    print("".join(["/---", "----" * 8, "\\"]))
-    for row in table:
-        print("".join(["|", "|".join(" %s " % (i or " ") for i in row), "|"]))
-    print("".join(["\\---", "----" * 8, "/"]))
-
-
-def solve(problem):
-    prolog.consult("sudoku.pl")
-    p = str(problem).replace("0", "_")
-    result = list(prolog.query("L=%s,sudoku(L)" % p, maxresult=1))
-    if result:
-        result = result[0]
-        return result["L"]
-    else:
-        return False
-
-
-def main():
-    puzzle = puzzle1
-    print("-- PUZZLE --")
-    pretty_print(puzzle)
-    print()
-    print(" -- SOLUTION --")
-    solution = solve(puzzle)
-    if solution:
-        pretty_print(solution)
-    else:
-        print("This puzzle has no solutions [is it valid?]")
-
-
-if __name__ == "__main__":
-    prolog = Prolog()
-    main()
diff --git a/examples/sudoku/sudoku_daily.py b/examples/sudoku/sudoku_daily.py
deleted file mode 100644
index 3ebf852..0000000
--- a/examples/sudoku/sudoku_daily.py
+++ /dev/null
@@ -1,102 +0,0 @@
-# -*- coding: utf-8 -*-
-
-# pyswip -- Python SWI-Prolog bridge
-# Copyright (c) 2007-2018 Yüce Tekol
-#
-# Permission is hereby granted, free of charge, to any person obtaining a copy
-# of this software and associated documentation files (the "Software"), to deal
-# in the Software without restriction, including without limitation the rights
-# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-# copies of the Software, and to permit persons to whom the Software is
-# furnished to do so, subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be included in all
-# copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-# SOFTWARE.
-
-
-# Sudoku auto-solver. Get today's sudoku at http://www.sudoku.org.uk/daily.asp
-# and solve it
-
-from __future__ import print_function
-from pyswip.prolog import Prolog
-from pyswip.easy import *
-
-from html.parser import HTMLParser
-
-import urllib.request as urllib_request
-
-
-class DailySudokuPuzzle(HTMLParser):
-    def __init__(self):
-        self.puzzle = []
-        self.__in_td = False
-        HTMLParser.__init__(self)
-
-    def handle_starttag(self, tag, attrs):
-        if tag == "td":
-            for attr in attrs:
-                if attr[0] == "class" and attr[1] == "InnerTDone":
-                    self.__in_td = True
-                    break
-        elif tag == "input":
-            if self.__in_td:
-                self.puzzle.append(0)
-
-    def handle_endtag(self, tag):
-        if tag == "td":
-            self.__in_td = False
-
-    def handle_data(self, data):
-        if self.__in_td:
-            self.puzzle.append(int(data))
-
-
-def pretty_print(table):
-    print("".join(["/---", "----" * 8, "\\"]))
-    for row in table:
-        print("".join(["|", "|".join(" %s " % (i or " ") for i in row), "|"]))
-    print("".join(["\\---", "----" * 8, "/"]))
-
-
-def get_daily_sudoku(url):
-    puzzle = DailySudokuPuzzle()
-    f = urllib_request.urlopen(url)
-    puzzle.feed(f.read().decode("latin-1"))
-    puzzle = puzzle.puzzle
-    return [puzzle[i * 9 : i * 9 + 9] for i in range(9)]
-
-
-def solve(problem):
-    prolog.consult("sudoku.pl")
-    p = str(problem).replace("0", "_")
-    result = list(prolog.query("Puzzle=%s,sudoku(Puzzle)" % p, maxresult=1))
-    if result:
-        result = result[0]
-        return result["Puzzle"]
-    else:
-        return False
-
-
-if __name__ == "__main__":
-    URL = "http://www.sudoku.org.uk/daily.asp"
-
-    prolog = Prolog()  # having this in `solve` bites! because of __del__
-    print("Getting puzzle from:", URL)
-    puzzle = get_daily_sudoku(URL)
-    print("-- PUZZLE --")
-    pretty_print(puzzle)
-    print()
-    print(" -- SOLUTION --")
-    solution = solve(puzzle)
-    if solution:
-        pretty_print(solution)
-    else:
-        print("This puzzle has no solutions [is it valid?]")
diff --git a/src/pyswip/examples/__init__.py b/src/pyswip/examples/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/examples/sudoku/sudoku.pl b/src/pyswip/examples/sudoku.pl
similarity index 100%
rename from examples/sudoku/sudoku.pl
rename to src/pyswip/examples/sudoku.pl
diff --git a/src/pyswip/examples/sudoku.py b/src/pyswip/examples/sudoku.py
new file mode 100644
index 0000000..955b8dc
--- /dev/null
+++ b/src/pyswip/examples/sudoku.py
@@ -0,0 +1,143 @@
+# -*- coding: utf-8 -*-
+
+# pyswip -- Python SWI-Prolog bridge
+# Copyright (c) 2007-2024 Yüce Tekol
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import sys
+from typing import List, Union, Literal
+from io import StringIO
+
+from pyswip.prolog import Prolog
+
+
+__all__ = "Matrix", "solve", "prolog_source"
+
+_DIMENSION = 9
+_SOURCE_PATH = "sudoku.pl"
+
+
+Prolog.consult(_SOURCE_PATH, relative_to=__file__)
+
+
+class Matrix:
+    def __init__(self, matrix: List[List[int]]) -> None:
+        if not matrix:
+            raise ValueError("matrix must be given")
+        if len(matrix) != _DIMENSION:
+            raise ValueError("Matrix dimension must be 9")
+        self._dimension = len(matrix)
+        self._validate(self._dimension, matrix)
+        self.matrix = matrix
+
+    @classmethod
+    def from_text(cls, text: str) -> "Matrix":
+        lines = text.strip().split("\n")
+        dimension = len(lines)
+        rows = []
+        for i, line in enumerate(lines):
+            cols = line.split()
+            if len(cols) != dimension:
+                raise ValueError(
+                    f"All rows must have {dimension} columns, line {i+1} has {len(cols)}"
+                )
+            rows.append([0 if x == "." else int(x) for x in cols])
+        return cls(rows)
+
+    @classmethod
+    def _validate(cls, dimension: int, matrix: List[List[int]]):
+        if len(matrix) != dimension:
+            raise ValueError(f"Matrix must have {dimension} rows, it has {len(matrix)}")
+        for i, row in enumerate(matrix):
+            if len(row) != dimension:
+                raise ValueError(
+                    f"All rows must have {dimension} columns, row {i+1} has {len(row)}"
+                )
+
+    def __len__(self) -> int:
+        return self._dimension
+
+    def __str__(self) -> str:
+        sio = StringIO()
+        self.pretty_print(file=sio)
+        return sio.getvalue()
+
+    def __repr__(self) -> str:
+        return str(self.matrix)
+
+    def pretty_print(self, *, file=sys.stdout) -> None:
+        for row in self.matrix:
+            row = " ".join(str(x or ".") for x in row)
+            print(row, file=file)
+
+
+def solve(matrix: Matrix) -> Union[Matrix, Literal[False]]:
+    """
+    Solves the given Sudoku puzzle
+
+    Parameters:
+        matrix (Matrix): The matrix that contains the Sudoku puzzle
+
+    Returns:
+        Matrix: Solution matrix
+        False: If no solutions was found
+    """
+    p = repr(matrix).replace("0", "_")
+    result = list(Prolog.query(f"L={p},sudoku(L)", maxresult=1))
+    if not result:
+        return False
+    result = result[0].get("L")
+    if not result:
+        return False
+    return Matrix(result)
+
+
+def prolog_source() -> str:
+    from pathlib import Path
+
+    path = Path(__file__).parent / _SOURCE_PATH
+    with open(path) as f:
+        return f.read()
+
+
+def main():
+    puzzle = Matrix.from_text("""
+. . 5 . 7 . 2 6 8
+. . 4 . . 2 . . .
+. . 1 . 9 . . . .
+. 8 . . . . 1 . .
+. 2 . 9 . . . 7 .
+. . 6 . . . . 3 .
+. . 2 . 4 . 7 . .
+. . . 5 . . 9 . .
+9 5 7 . 3 . . . .    
+    """)
+    print("\n-- PUZZLE --")
+    puzzle.pretty_print()
+    print("\n-- SOLUTION --")
+    solution = solve(puzzle)
+    if solution:
+        solution.pretty_print()
+    else:
+        print("This puzzle has no solutions. Is it valid?")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/src/pyswip/prolog.py b/src/pyswip/prolog.py
index 569edff..192854a 100644
--- a/src/pyswip/prolog.py
+++ b/src/pyswip/prolog.py
@@ -218,14 +218,13 @@ def query(cls, query, maxresult=-1, catcherrors=True, normalize=True):
         If the query is a yes/no question, returns {} for yes, and nothing for no.
         Otherwise returns a generator of dicts with variables as keys.
 
-        >>> prolog = Prolog()
-        >>> prolog.assertz("father(michael,john)")
-        >>> prolog.assertz("father(michael,gina)")
-        >>> bool(list(prolog.query("father(michael,john)")))
+        >>> Prolog.assertz("father(michael,john)")
+        >>> Prolog.assertz("father(michael,gina)")
+        >>> bool(list(Prolog.query("father(michael,john)")))
         True
-        >>> bool(list(prolog.query("father(michael,olivia)")))
+        >>> bool(list(Prolog.query("father(michael,olivia)")))
         False
-        >>> print sorted(prolog.query("father(michael,X)"))
+        >>> print sorted(Prolog.query("father(michael,X)"))
         [{'X': 'gina'}, {'X': 'john'}]
         """
         return cls._QueryWrapper()(query, maxresult, catcherrors, normalize)
diff --git a/tests/examples/__init__.py b/tests/examples/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/examples/test_sudoku.py b/tests/examples/test_sudoku.py
new file mode 100644
index 0000000..2cc35be
--- /dev/null
+++ b/tests/examples/test_sudoku.py
@@ -0,0 +1,58 @@
+import unittest
+
+from pyswip.examples.sudoku import Matrix, solve, prolog_source
+
+
+class MatrixTestCase(unittest.TestCase):
+    FIXTURE = """
+. 6 . 1 . 4 . 5 .
+. . 8 3 . 5 6 . .
+2 . . . . . . . 1
+8 . . 4 . 7 . . 6
+. . 6 . . . 3 . .
+7 . . 9 . 1 . . 4
+5 . . . . . . . 2
+. . 7 2 . 6 9 . .
+. 4 . 5 . 8 . 7 .
+    """
+
+    def test_matrix_from_text(self):
+        got = Matrix.from_text(self.FIXTURE)
+        target = [
+            [0, 6, 0, 1, 0, 4, 0, 5, 0],
+            [0, 0, 8, 3, 0, 5, 6, 0, 0],
+            [2, 0, 0, 0, 0, 0, 0, 0, 1],
+            [8, 0, 0, 4, 0, 7, 0, 0, 6],
+            [0, 0, 6, 0, 0, 0, 3, 0, 0],
+            [7, 0, 0, 9, 0, 1, 0, 0, 4],
+            [5, 0, 0, 0, 0, 0, 0, 0, 2],
+            [0, 0, 7, 2, 0, 6, 9, 0, 0],
+            [0, 4, 0, 5, 0, 8, 0, 7, 0],
+        ]
+        self.assertListEqual(target, got.matrix)
+
+    def test_solve_success(self):
+        puzzle = Matrix.from_text(self.FIXTURE)
+        solution = solve(puzzle)
+        target = [
+            [9, 6, 3, 1, 7, 4, 2, 5, 8],
+            [1, 7, 8, 3, 2, 5, 6, 4, 9],
+            [2, 5, 4, 6, 8, 9, 7, 3, 1],
+            [8, 2, 1, 4, 3, 7, 5, 9, 6],
+            [4, 9, 6, 8, 5, 2, 3, 1, 7],
+            [7, 3, 5, 9, 6, 1, 8, 2, 4],
+            [5, 8, 9, 7, 1, 3, 4, 6, 2],
+            [3, 1, 7, 2, 4, 6, 9, 8, 5],
+            [6, 4, 2, 5, 9, 8, 1, 7, 3],
+        ]
+        self.assertEqual(target, solution.matrix)
+
+    def test_solve_failure(self):
+        fixture = " 8" + self.FIXTURE[2:]
+        puzzle = Matrix.from_text(fixture)
+        solution = solve(puzzle)
+        self.assertFalse(solution)
+
+    def test_prolog_source(self):
+        text = prolog_source()
+        self.assertIn("Prolog Sudoku Solver", text)
diff --git a/tests/test_examples.py b/tests/test_examples.py
index d48acf3..0dd8059 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -26,280 +26,26 @@
 ensure stability in several platforms.
 """
 
-import unittest
-
 import pytest
 
 from pyswip import *
 
+examples = [
+    "create_term.py",
+    "father.py",
+    "register_foreign.py",
+    "register_foreign_simple.py",
+    "knowledgebase.py",
+    "hanoi/hanoi_simple.py",
+    "sendmoremoney/money.py",
+    "sendmoremoney/money_new.py",
+]
 
-class TestExamples(unittest.TestCase):
-    """
-    Each test method is named after one example in $PYSWIP/examples.
-
-    WARNING: Since it is not possible to unload things from the Prolog base, the
-    examples have to be 'orthogonal'.
-
-    """
-
-    def test_create_term(self):
-        """
-        Simple example of term creation.
-        """
-
-        prolog = Prolog()
-
-        a1 = PL_new_term_refs(2)
-        a2 = a1 + 1
-        t = PL_new_term_ref()
-        ta = PL_new_term_ref()
-
-        animal2 = PL_new_functor(PL_new_atom("animal"), 2)
-        assertz = PL_new_functor(PL_new_atom("assertz"), 1)
-
-        PL_put_atom_chars(a1, "gnu")
-        PL_put_integer(a2, 50)
-        PL_cons_functor_v(t, animal2, a1)
-        PL_cons_functor_v(ta, assertz, t)
-        PL_call(ta, None)
-
-        result = list(prolog.query("animal(X,Y)", catcherrors=True))
-        self.assertEqual(len(result), 1)
-        self.assertEqual(result[0], {"X": "gnu", "Y": 50})
-
-    def test_knowledgebase(self):
-        """
-        Tests usage of modules.
-        """
-
-        _ = Prolog()
-
-        assertz = Functor("assertz")
-        parent = Functor("parent", 2)
-        test1 = newModule("test1")
-        test2 = newModule("test2")
-
-        call(assertz(parent("john", "bob")), module=test1)
-        call(assertz(parent("jane", "bob")), module=test1)
-
-        call(assertz(parent("mike", "bob")), module=test2)
-        call(assertz(parent("gina", "bob")), module=test2)
-
-        # Test knowledgebase module test1
-
-        result = set()
-        X = Variable()
-        q = Query(parent(X, "bob"), module=test1)
-        while q.nextSolution():
-            result.add(X.value.value)  # X.value is an Atom
-        q.closeQuery()
-        self.assertEqual(result, set(["john", "jane"]))
-
-        # Test knowledgebase module test2
-
-        result = set()
-        q = Query(parent(X, "bob"), module=test2)
-        while q.nextSolution():
-            result.add(X.value.value)
-        q.closeQuery()
-        self.assertEqual(result, set(["mike", "gina"]))
-
-    def test_father(self):
-        """
-        Tests basic inferences.
-        """
-
-        p = Prolog()
-
-        father = Functor("father", 2)
-        mother = Functor("mother", 2)
-
-        p.assertz("father(john,mich)")
-        p.assertz("father(john,gina)")
-        p.assertz("mother(jane,mich)")
-
-        Y = Variable()
-        Z = Variable()
-
-        result = []
-        q = Query(father("john", Y), mother(Z, Y))
-        while q.nextSolution():
-            y = Y.value.value
-            z = Z.value.value
-            result.append({"Y": y, "Z": z})
-        q.closeQuery()
-
-        self.assertEqual(len(result), 1)
-        self.assertEqual(result[0], {"Y": "mich", "Z": "jane"})
-
-        # Repeat the same query but using strings
-        result = []
-        for s in p.query("father(john,Y),mother(Z,Y)"):
-            result.append(s)
-        self.assertEqual(len(result), 1)
-        self.assertEqual(result[0], {"Y": "mich", "Z": "jane"})
-
-    def test_coins(self):
-        """
-        Runs the coins example (uses clp library of SWI-Prolog).
-        """
-
-        prolog = Prolog()
-        prolog.consult(example_path("coins/coins.pl"))
-        count = 100
-        total = 500
-        coins = Functor("coins", 3)
-        S = Variable()
-        q = Query(coins(S, count, total))
-
-        solutions = []
-        while q.nextSolution():
-            solutions.append(S.value)
-        q.closeQuery()
 
-        self.assertEqual(len(solutions), 105)
-
-        # Now do the same test, but using the prolog.query interface
-        solutions = list(prolog.query("coins(S, %d, %d)." % (count, total)))
-        self.assertEqual(len(solutions), 105)
-
-    def test_draughts(self):
-        """
-        Runs the draughts example (uses clp library of SWI-Prolog).
-        """
-
-        prolog = Prolog()
-        prolog.consult(example_path("draughts/puzzle1.pl"))
-        solutions = []
-        for soln in prolog.query("solve(B)."):
-            solutions.append(soln["B"])
-        self.assertEqual(len(solutions), 37)
-
-        # Now do the same test, but using the prolog.query interface
-        solutions = list(prolog.query("solve(B)."))
-        self.assertEqual(len(solutions), 37)
-
-    def test_hanoi(self):
-        """
-        Runs the hanoi example.
-        """
-
-        N = 3  # Number of disks
-
-        result = []
-
-        def notify(t):
-            result.append((t[0].value, t[1].value))
-
-        notify.arity = 1
-
-        prolog = Prolog()
-        registerForeign(notify)
-        prolog.consult(example_path("hanoi/hanoi.pl"))
-        list(prolog.query("hanoi(%d)" % N))  # Forces the query to run completely
-
-        self.assertEqual(len(result), 7)
-        self.assertEqual(result[0], ("left", "right"))
-        self.assertEqual(result[1], ("left", "center"))
-        self.assertEqual(result[2], ("right", "center"))
-
-    def test_sendmoremoney(self):
-        """
-        Runs the sendmoremoney example::
-
-            S E N D
-            M O R E
-          + -------
-          M O N E Y
-
-        So, what should be the values of S, E, N, D, M, O, R, Y
-        if they are all distinct digits.
-        """
-
-        letters = "S E N D M O R Y".split()
-        prolog = Prolog()
-        sendmore = Functor("sendmore")
-        prolog.consult(example_path("sendmoremoney/money.pl"))
-
-        X = Variable()
-        call(sendmore(X))
-        r = X.value
-        val = {}
-        for i, letter in enumerate(letters):
-            val[letter] = r[i]
-
-        self.assertEqual(len(val), 8)
-
-        send = val["S"] * 1e3 + val["E"] * 1e2 + val["N"] * 1e1 + val["D"] * 1e0
-        more = val["M"] * 1e3 + val["O"] * 1e2 + val["R"] * 1e1 + val["E"] * 1e0
-        money = (
-            val["M"] * 1e4
-            + val["O"] * 1e3
-            + val["N"] * 1e2
-            + val["E"] * 1e1
-            + val["Y"] * 1e0
-        )
-        self.assertEqual(money, send + more)
-
-    def test_sudoku(self):
-        """
-        Runs the sudoku example (uses clp library of SWI-Prolog).
-        """
-
-        _ = 0
-        puzzle1 = [
-            [_, 6, _, 1, _, 4, _, 5, _],
-            [_, _, 8, 3, _, 5, 6, _, _],
-            [2, _, _, _, _, _, _, _, 1],
-            [8, _, _, 4, _, 7, _, _, 6],
-            [_, _, 6, _, _, _, 3, _, _],
-            [7, _, _, 9, _, 1, _, _, 4],
-            [5, _, _, _, _, _, _, _, 2],
-            [_, _, 7, 2, _, 6, 9, _, _],
-            [_, 4, _, 5, _, 8, _, 7, _],
-        ]
-
-        puzzle2 = [
-            [_, _, 1, _, 8, _, 6, _, 4],
-            [_, 3, 7, 6, _, _, _, _, _],
-            [5, _, _, _, _, _, _, _, _],
-            [_, _, _, _, _, 5, _, _, _],
-            [_, _, 6, _, 1, _, 8, _, _],
-            [_, _, _, 4, _, _, _, _, _],
-            [_, _, _, _, _, _, _, _, 3],
-            [_, _, _, _, _, 7, 5, 2, _],
-            [8, _, 2, _, 9, _, 7, _, _],
-        ]
-
-        prolog = Prolog()
-        prolog.consult(example_path("sudoku/sudoku.pl"))
-
-        for i, problem in enumerate((puzzle1, puzzle2)):
-            p = str(problem).replace("0", "_")
-            result = list(prolog.query("L=%s,sudoku(L)" % p, maxresult=1))
-            if result:
-                # Does a simple check on the result
-                result = result[0]
-                for j, line in enumerate(result["L"]):
-                    self.assertEqual(
-                        len(set(line)), 9, "Failure in line %d: %s" % (j, line)
-                    )
-            else:
-                self.fail("Failed while running example number %d" % i)
-
-    @pytest.mark.slow
-    def test_large_db(self):
-        """
-        Generates a large database, then runs query
-        """
-
-        num_facts = 125000
-        prolog = Prolog()
-        for i in range(num_facts):
-            prolog.assertz("p(%s)" % i)
-
-        results = [r for r in prolog.query("p(I)")]
-        self.assertEqual(len(results), num_facts)
+@pytest.mark.parametrize("example", examples)
+def test_example(example):
+    path = example_path(example)
+    execfile(path)
 
 
 def example_path(path):
@@ -310,3 +56,16 @@ def example_path(path):
             os.path.split(os.path.abspath(__file__))[0], "..", "examples", path
         )
     ).replace("\\", "\\\\")
+
+
+def execfile(filepath, globals=None, locals=None):
+    if globals is None:
+        globals = {}
+    globals.update(
+        {
+            "__file__": filepath,
+            "__name__": "__main__",
+        }
+    )
+    with open(filepath, "rb") as file:
+        exec(compile(file.read(), filepath, "exec"), globals, locals)
diff --git a/tests/test_foreign.py b/tests/test_foreign.py
index 12a654c..d9a7249 100644
--- a/tests/test_foreign.py
+++ b/tests/test_foreign.py
@@ -23,10 +23,9 @@ def hello(t):
 
         registerForeign(hello)
 
-        prolog = Prolog()
-        prolog.assertz("father(michael,john)")
-        prolog.assertz("father(michael,gina)")
-        result = list(prolog.query("father(michael,X), hello(X)"))
+        Prolog.assertz("mother(emily,john)")
+        Prolog.assertz("mother(emily,gina)")
+        result = list(Prolog.query("mother(emily,X), hello(X)"))
         self.assertEqual(len(result), 2, "Query should return two results")
         for name in ("john", "gina"):
             self.assertTrue(
@@ -34,8 +33,6 @@ def hello(t):
             )
 
     def test_nondeterministic_foreign(self):
-        prolog = Prolog()
-
         def nondet(a, context):
             control = PL_foreign_control(context)
             context = PL_foreign_context(context)
@@ -55,7 +52,7 @@ def nondet(a, context):
 
         nondet.arity = 1
         registerForeign(nondet, flags=PL_FA_NONDETERMINISTIC)
-        result = list(prolog.query("nondet(X)"))
+        result = list(Prolog.query("nondet(X)"))
 
         self.assertEqual(len(result), 10, "Query should return 10 results")
         for i in range(10):
@@ -78,9 +75,7 @@ def test_for_string(string, test_result):
         registerForeign(get_str)
         registerForeign(test_for_string)
 
-        prolog = Prolog()
-
-        result = list(prolog.query("get_str(String), test_for_string(String, Result)"))
+        result = list(Prolog.query("get_str(String), test_for_string(String, Result)"))
         self.assertEqual(
             result[0]["Result"],
             "true",
@@ -100,17 +95,14 @@ def get_list_of_lists(result):
 
         registerForeign(get_list_of_lists)
 
-        prolog = Prolog()
-
-        result = list(prolog.query("get_list_of_lists(Result)"))
+        result = list(Prolog.query("get_list_of_lists(Result)"))
         self.assertTrue(
             {"Result": [[1], [2]]} in result,
             "Nested lists should be unified correctly as return value.",
         )
 
     def test_dictionary(self):
-        prolog = Prolog()
-        result = list(prolog.query("X = dict{key1:value1 , key2: value2}"))
+        result = list(Prolog.query("X = dict{key1:value1 , key2: value2}"))
         dict = result[0]
         self.assertTrue(
             {"key1": "value1", "key2": "value2"} == dict["X"],
@@ -118,8 +110,7 @@ def test_dictionary(self):
         )
 
     def test_empty_dictionary(self):
-        prolog = Prolog()
-        result = list(prolog.query("X = dict{}"))
+        result = list(Prolog.query("X = dict{}"))
         dict = result[0]
         self.assertTrue(
             dict["X"] == {},
@@ -127,8 +118,7 @@ def test_empty_dictionary(self):
         )
 
     def test_nested_dictionary(self):
-        prolog = Prolog()
-        result = list(prolog.query("X = dict{key1:nested{key:value} , key2: value2}"))
+        result = list(Prolog.query("X = dict{key1:nested{key:value} , key2: value2}"))
         dict = result[0]
         self.assertTrue(
             {"key1": {"key": "value"}, "key2": "value2"} == dict["X"],
diff --git a/tests/test_issues.py b/tests/test_issues.py
index ba4c437..01a7c6a 100644
--- a/tests/test_issues.py
+++ b/tests/test_issues.py
@@ -68,8 +68,7 @@ def test_issue_1(self):
         # issue 13, if it does not work, it will segfault Python.
         from pyswip import Prolog
 
-        prolog = Prolog()
-        prolog.assertz("randomTerm(michael,john)")
+        Prolog.assertz("randomTerm(michael,john)")
 
     def test_issue_8(self):
         """
@@ -89,10 +88,9 @@ def hello(t):
 
         registerForeign(hello)
 
-        prolog = Prolog()
-        prolog.assertz("parent(michael,john)")
-        prolog.assertz("parent(michael,gina)")
-        p = prolog.query("parent(michael,X), hello(X)")
+        Prolog.assertz("parent(michael,john)")
+        Prolog.assertz("parent(michael,gina)")
+        p = Prolog.query("parent(michael,X), hello(X)")
         result = list(p)  # Will run over the iterator
 
         self.assertEqual(len(callsToHello), 2)  # ['john', 'gina']
@@ -246,13 +244,12 @@ def test_issue_62(self):
         """
         from pyswip import Prolog
 
-        prolog = Prolog()
-        prolog.consult("test_unicode.pl", catcherrors=True, relative_to=__file__)
-        atoms = list(prolog.query("unicode_atom(B)."))
+        Prolog.consult("test_unicode.pl", catcherrors=True, relative_to=__file__)
+        atoms = list(Prolog.query("unicode_atom(B)."))
 
         self.assertEqual(len(atoms), 3, "Query should return exactly three atoms")
 
-        strings = list(prolog.query("unicode_string(B)."))
+        strings = list(Prolog.query("unicode_string(B)."))
 
         self.assertEqual(len(strings), 1, "Query should return exactly one string")
         self.assertEqual(strings[0]["B"], b"\xd1\x82\xd0\xb5\xd1\x81\xd1\x82")
diff --git a/tests/test_prolog.py b/tests/test_prolog.py
index a870789..a84b870 100644
--- a/tests/test_prolog.py
+++ b/tests/test_prolog.py
@@ -112,7 +112,6 @@ def test_prolog_read_file(self):
         See: https://github.com/yuce/pyswip/issues/10
         """
         current_dir = os.path.dirname(os.path.abspath(__file__))
-        prolog = pl.Prolog()
         path = os.path.join(current_dir, "test_read.pl")
-        prolog.consult(path)
-        list(prolog.query(f'read_file("{path}", S)'))
+        pl.Prolog.consult(path)
+        list(pl.Prolog.query(f'read_file("{path}", S)'))