pygame写完这段为什么编译不了呀

import sys
import pygame

def run_game():
	pygame.init()
	screen = pygame.display.set.mode((1200,800))
	pygame.display.set.caption("Alien Invasin")
	
	while True:
		for event in pygame.event.get():
			if event.type == pygame.QUIT:
				sys.exit()
				
	    pygame.display.flip()
	    
run_game()	    

是set_mode、set_caption