pygame问题

flyps

我在制作游戏时调用了下文的say函数，程序却卡住了，这是怎么回事

import pygame
from pygame.locals import *
pygame.init()
Acolour = (255, 255, 255)
def changeC(colour, acolour = Acolour):
    acolour = colour
def say(story, surface, size, afont, k, colour = Acolour):
    Astory = list(story)
    Bstory = ""
    for i in Astory:
        Bstory = "".join([Bstory, i])
        pygame.draw.rect(surface, colour, (size[0]/2, size[1]/2, size[0], size[1]/4), 10)
        surface.blit(afont.render(Bstory, True, colour), (size[0]/2, size[1]/2))
    while not k[K_z]:
        surface.blit(afont.render(Bstory, True, colour), (size[0]/2, size[1]/2))
    pygame.time.delay(10)