Listing 9. Completion of the moveBall function.
  //Now draw the ball on the background at the new
  // location.
  circlefill (buffer,x,y,radius,makecol(255,0,0));

  //Call the blit function to copy the off-screen buffer
  // contents to the screen.
  blit(buffer,screen,0,0,0,0,width,height);

  rest(5);//Delay for five milliseconds
}// end moveBall function.