Python精灵模块的collide_edge碰到边缘指令

from sprites import Sprite,mouse_pos,Screen

screen = Screen()      # 新建窗口

bug = Sprite()
bug.gotorandom()

while True:
    mx,my = mouse_pos()   # 鼠标指针坐标
    bug.goto(mx,my)
    r = bug.collide_edge()
    if r:  # 如果bug碰到鼠标指针 
        if r[0]==1:screen.title('碰到上边缘')
        elif r[1]==1:screen.title('碰到下边缘')
        elif r[2]==1:screen.title('碰到左边缘')
        elif r[3]==1:screen.title('碰到右边缘')        
    else:
        screen.title('没碰到边缘')
    screen.update()