added variety of free squares

bingo.py

@@ -10,13 +10,13 @@ class Bingo:
         self.X_OFFSET  = 10
         self.Y_OFFSET = 110
         self.SQUARES_PATH = "bingo_images/squares/*.png"
-        self.FREE_SQUARE_PATH = "bingo_images/free_space.png"
+        self.FREE_SQUARES_PATH = "bingo_images/free_squares/*.png"
         self.BLANK_CARD_PATH = "bingo_images/card_blank.png"
         self.TEMP_FOLDER = "bingo_images/temp/"
 
-        self.square_files = glob.glob(self.SQUARES_PATH)
-
     def get_card(self):
+        square_files = glob.glob(self.SQUARES_PATH)
+        free_square_files = glob.glob(self.FREE_SQUARES_PATH)
         used_files = set()
 
         with Image.open(self.BLANK_CARD_PATH) as card_img:
@@ -27,17 +27,18 @@ class Bingo:
         for y in range(5):
             for x in range(5):
                 square_file = ""
-                # If this is the center square, use the free square
+                # If this is the center square, pick a random free square
                 if x == 2 and y == 2:
-                    square_file = self.FREE_SQUARE_PATH
+                    square_file = \
+                        free_square_files[randrange(len(free_square_files))]
 
                 # otherwise, find a random file that hasn't been used yet
                 else:
-                    rand_file_idx = randrange(len(self.square_files))
+                    rand_file_idx = randrange(len(square_files))
                     while rand_file_idx in used_files:
-                        rand_file_idx = randrange(len(self.square_files))
+                        rand_file_idx = randrange(len(square_files))
 
-                    square_file = self.square_files[rand_file_idx]
+                    square_file = square_files[rand_file_idx]
                     used_files.add(rand_file_idx)
                 
                 with Image.open(square_file) as square: