save project

snake.py

@@ -62,6 +62,7 @@ while True:
         score+=1
     else:
         position.pop(0)
+    if x<0 or y<0 or y>630 or x>630:
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去