new_contents: import sys, pygame
  pygame.init()
  
  size = width, height = 320, 240
  speed = [2, 2]
  black = 0, 0, 0
  
  screen = pygame.display.set_mode(size)
  
  #ball = pygame.image.load("ball.bmp")
  ball = pygame.surface.Surface((100, 100))
  ball.fill(pygame.Color(0, 0, 255, 255))
  ballrect = ball.get_rect()
  clock = pygame.time.Clock()
  
  while 1:
      for event in pygame.event.get():
          if event.type == pygame.QUIT:
              sys.exit()
  
      ballrect = ballrect.move(speed)
      if ballrect.left < 0 or ballrect.right > width:
          speed[0] = -speed[0]
      if ballrect.top < 0 or ballrect.bottom > height:
          speed[1] = -speed[1]
  
      screen.fill(black)
      screen.blit(ball, ballrect)
      pygame.display.flip()
      clock.tick(40)
  
subject: Add simple animation example from pygame tutorial