little change

main.py

@@ -8,7 +8,7 @@ class Main:
     def main (cls) -> None:
         pygame.init ()
 
-        screen = pygame.display.set_mode ((640, 480))
+        screen: pygame.Surface = pygame.display.set_mode ((640, 480))
 
         while (True):
             screen.fill ((255, 255, 255))