save project

snake.py

@@ -60,7 +60,9 @@ while True:
            apple_y=30*num2-30
         else:
                position.pop(0)
-    position.pop(0)
+               if x < 0 or x >630 or y < 0 or y > 450:
+                   exit()
+   
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去