import pygame

pygame.init()

screen = pygame.display.set_mode((640, 480))
pygame.display.set_caption("Moving Rectangle")
clock = pygame.time.Clock()

BG   = (20, 20, 20)
BLUE = (60, 120, 220)

x = 0
y = 200
speed = 3

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    # move the rectangle to the right each frame
    x += speed

    # wrap around when it goes off screen
    if x > 640:
        x = -60

    screen.fill(BG)
    pygame.draw.rect(screen, BLUE, (x, y, 60, 40))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()