Чёрный экран при запуске программы с pygame

import pygame
pygame.init ()
BLACK = ( 0, 0, 0)
WHITE = (255, 255, 255)
BLUE = ( 0, 0, 255)
GREEN = ( 0, 255, 0)
RED = ( 255, 0, 0)
size = [400, 300]
screen = pygame.display.set_mode(size)
pygame.display.set_caption("Пример рисования")
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            exit()
screen.fill(WHITE)
pygame.draw.line(screen, BLACK, [0, 0], [40, 40], 4)
pygame.draw.lines(screen, GREEN, False, [[60, 20], [100, 20], [140, 5], [180,20], [220,20]], 4)
pygame.draw.aaline(screen, BLACK, [0, 50], [40, 90], 2)
pygame.draw.rect(screen, BLUE, [60,60,60,60], 1)
pygame.draw.rect(creen, BLUE, [140, 60,60,60])
pygame.draw.circle(screen, BLACK, [90,170], 30, 1)
pygame.draw.circle(screen, BLACK, [170, 170], 30)
pygame.draw.ellipse(screen, RED, [60,220,60,30], 1)
pygame.draw.ellipse(screen, RED, [140,220,60,30])
pygame.draw.polygon(screen, BLACK, [[170, 25], [140, 60], [200,60]], 5)
pygame.draw.arc(screen, RED, [210, 75, 50, 125], 0, pi/2, 3)
pygame.draw.arc(screen, GREEN, [210, 75, 150, 125], pi/2, pi, 3)
pygame.draw.arc(screen, BLUE, [210, 75, 150, 125], pi/2, 3)
pygame.draw.arc(screen, BLACK, [210, 75, 150, 125], 3*pi/2, 2*pi, 3)
pygame.display.flip()
pygame.quit()