Add comments to pygame example

examples/GPIOZero_PyGame/example.py

@@ -1,31 +1,39 @@
 from gpiozero import Button
 import pygame
-
 from Player import Player
 
+# Initialize pygame
 pygame.init()
 
+# Create screen of 500x500 pixels
 screen = pygame.display.set_mode([500, 500])
 
+# Initialize the physical GPIO inputs
 left_button = Button(5)
 down_button = Button(6) 
 up_button = Button(13)
 right_button = Button(19)
 
+# Initialize Player sprite class
 player = Player()
 
+
+# Run continous game loop
 while True:
+   # Check state of physical inputs
    if left_button.is_pressed:
       player.move_left(2)
-   elif down_button.is_pressed:
+   if down_button.is_pressed:
       player.move_down(2)
-   elif right_button.is_pressed:
+   if right_button.is_pressed:
       player.move_right(2)
-   elif up_button.is_pressed:
+   if up_button.is_pressed:
       player.move_up(2)
 
+   # Fill screen with black background
    screen.fill((0, 0, 0))
 
+   # Place the player on the screen
    screen.blit(player.surf, player.rect)
 
    # Flip the display