Actionscript 3.0 - EnterFrame

ball_mc.addEventListener(Event.ENTER_FRAME, moveBall);

function moveBall(event:Event):void
{
if (ball_mc.x < stage.stageWidth - ball_mc.width && ball_mc.y < stage.stageHeight - ball_mc.height)
{
ball_mc.x += 5;
ball_mc.y += 1;
}
else
{
ball_mc.removeEventListener(Event.ENTER_FRAME, moveBall);
}
}