save project

snake.py

@@ -62,6 +62,8 @@ while True:
         ns+= 1
     else:
         position.pop(0) 
+    if x < 0 or x > 630 or y < 0 or y >450:
+        
 
     # 将背景图画上去
     screen.blit(background, (0, 0))