pygame 按键松开

while True:
    pygame.display.update()
    event_list = pygame.event.get()
    for event in event_list:
        if event.type == pygame.QUIT:
            sys.exit()
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                sys.exit()
            if event.key == pygame.K_RETURN:
                typingEnter = True
            if   按键松开 :
                typingEnter = False

如何检测按键松开事件？

    if event.type == pygame.KEYUP: