Add type and predicate methods to Photo and Video.

Since collections endpoints can return both, it will be helpful to have a way to distinguish.

lib/pexels/photo.rb

@@ -22,4 +22,16 @@ def initialize(attrs)
   rescue KeyError => exception
     raise Pexels::MalformedAPIResponseError.new(exception)
   end
+
+  def type
+    'Photo'
+  end
+
+  def photo?
+    true
+  end
+
+  def video?
+    false
+  end
 end

lib/pexels/video.rb

@@ -31,4 +31,16 @@ def initialize(attrs)
   rescue KeyError => exception
     raise Pexels::MalformedAPIResponseError.new(exception)
   end
+
+  def type
+    'Video'
+  end
+
+  def photo?
+    false
+  end
+
+  def video?
+    true
+  end
 end

test/photo_test.rb

@@ -60,6 +60,10 @@ def test_get_photo
     assert_equal photo.user.url, @photo.user.url
     assert_equal photo.user.id, @photo.user.id
     assert_equal photo.src, @photo.src
+
+    assert photo.photo?
+    assert_equal photo.type, 'Photo'
+    refute photo.video?
   end
 
   def test_invalid_get_photo

test/video_test.rb

@@ -57,6 +57,10 @@ def test_get_video
     assert_equal video.height, @video.height
     assert_equal video.url, @video.url
 
+    assert video.video?
+    assert_equal video.type, 'Video'
+    refute video.photo?
+
     assert video.user.is_a?(Pexels::User)
     assert_equal video.user.name, @video.user.name
     assert_equal video.user.url, @video.user.url