pygame退出要调用pygame.quit()

pygame处理键盘事件一般是使用如下代码：

import pygame as py
py.init()
for event in py.event.get():
    if event.type== py.QUIT:
        sys.exit()
    elif event.type==py.KEYDOWN:
        if event.key==py.K_ESCAPE:
            print "exit"
            sys.exit()
            py.quit()
        elif event.key==py.K_UP:
            print "up"
        elif event.key==py.K_LEFT:
            print "left"
        elif event.key==py.K_DOWN:
            print "down"
        elif event.key==py.K_RIGHT:
            print "right"