text: background_image_filename = 'sushiplate.jpg'
  sprite_image_filename = 'fugu.png'
  
  import pygame
  from pygame.locals import *
  from sys import exit
  
  pygame.init()
  
  screen = pygame.display.set_mode((640, 480), 0, 32)
  
  background = pygame.image.load(background_image_filename).convert()
  sprite = pygame.image.load(sprite_image_filename)
  
  # Our clock object
  clock = pygame.time.Clock()
  
  x1 = 0.
  x2 = 0.
  # Speed in pixels per second
  speed = 250.
  
  frame_no = 0
  
  while True:
      
      for event in pygame.event.get():
          if event.type == QUIT:
              exit()
      
      screen.blit(background, (0,0))
      screen.blit(sprite, (x1, 50))
      screen.blit(sprite, (x2, 250))
      
      time_passed = clock.tick()
      time_passed_seconds = time_passed / 1000.0
      
      distance_moved = time_passed_seconds * speed
      x1 += distance_moved
      
      if (frame_no % 5) == 0:
          distance_moved = time_passed_seconds * speed
          x2 += distance_moved * 5.
      
      # If the image goes off the end of the screen, move it back
      if x1 > 640.:
          x1 -= 640.    
      if x2 > 640.:
          x2 -= 640.  
          
      pygame.display.update()
      frame_no += 1
  