timer pythongame

1import pygame
2pygame.init()
3screen = pygame.display.set_mode((128, 128))
4clock = pygame.time.Clock()
5
6counter, text = 10, '10'.rjust(3)
7pygame.time.set_timer(pygame.USEREVENT, 1000)
8font = pygame.font.SysFont('Consolas', 30)
9
10while True:
11    for e in pygame.event.get():
12        if e.type == pygame.USEREVENT: 
13            counter -= 1
14            text = str(counter).rjust(3) if counter > 0 else 'boom!'
15        if e.type == pygame.QUIT: break
16    else:
17        screen.fill((255, 255, 255))
18        screen.blit(font.render(text, True, (0, 0, 0)), (32, 48))
19        pygame.display.flip()
20        clock.tick(60)
21        continue
22    break