如何在pygame中轮换线条？

import pygame
import sys

pygame.init()
width, height = 800, 600
screen = pygame.display.set_mode((width, height))

start_pos = (100, 100)
end_pos = (700, 500)

colors = [(255, 0, 0), (0, 255, 0), (0, 0, 255)]

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    # 清空屏幕
    screen.fill((0, 0, 0))

    # 绘制线条
    pygame.draw.line(screen, colors[0], start_pos, end_pos, 5)

    # 轮换线条颜色
    colors.append(colors.pop(0))

    # 更新屏幕显示
    pygame.display.flip()