import pygame, sys
from pygame. locals import *

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

surface = pygame.Surface((50, 50))
surface.fill((0,255,0))

pygame.display.set_caption("Hello World!")

while True: #main game loop
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
    pygame.display.update()