UnboundLocalError：pygame音乐播放并停止运行（在按键时）

Question

I'm trying to play and stop a music in my main page.

It's kind of weird. From my code, if the user press "m", suppose, the music should be off. However, the music didn't off. It continue

UnboundLocalError: local variable 'music_playing' referenced before assignment  

Can someone help me with my code?

pickUpSound = pygame.mixer.music.load('test.mp3')
pygame.mixer.music.play(-1)
music_playing = True

def mainMenu():
    main = pygame.image.load('menu.jpg')
    screen.blit(main,(0,0))
    while True:
        pygame.display.update()
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                quit()
            if event.type == KEYDOWN:
                if event.key == ord('m'):
                    if music_playing:
                        pygame.mixer.music.stop()
                    else:
                        pygame.mixer.music.play(-1)
                    music_playing = not music_playing

Answer 1

As it is written, event.type should be simultaneously equal to KEYDOWN and pygame.K_KP_ENTER at the same time. The second should be event.key instead of event.type .

if event.key == pygame.K_KP_ENTER:

EDIT There seems to be something wrong with the "keypad enter" key, I commented the problematic line (maybe try with another key, for example, I used K_a, and was able to start/stop by pressing "a")

import pygame

def mainMenu():
    pygame.display.init()
    pygame.display.set_mode([128,128])
    screen = pygame.display.get_surface()
    #                          
    pygame.mixer.init()
    pickUpSound = pygame.mixer.music.load('test.mp3')
    pygame.mixer.music.play(-1)
    music_playing = True
    #                          
    main = pygame.image.load('menu.jpg')
    screen.blit(main,(0,0))
    while True:
    pygame.display.update()
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()
        if event.type == pygame.KEYDOWN:
            #if event.key == pygame.K_KP_ENTER:
                if music_playing:
                    pygame.mixer.music.stop()
                    print "stopping"
                else:
                    pygame.mixer.music.play(-1)
                    print "playing"
                music_playing = not music_playing

mainMenu()

nb When running this code, I see the messages "playing" and "stopping" each time I press any key.

With if event.key == pygame.K_a: the music should start/stop by pressing "a".