set boundaries in flash - actionscript-3

Question

I want to set boundaries to my movie clip in flash with as3 so that the movie clip can't move out of the stage. How can i do this? This is the code that i have now. How i can now set the boundaries?
bij_mc.links_mc.play();
bij_mc.rechts_mc.play();
stage.addEventListener(KeyboardEvent.KEY_DOWN,beweeg);
stage.addEventListener(KeyboardEvent.KEY_UP,stopbeweeg);
function beweeg(evt:KeyboardEvent):void {
if (evt.keyCode==Keyboard.LEFT) {
bij_mc.links_mc.x -=10;
bij_mc.rechts_mc.x -=10;
bij_mc.lichaam_mc.x -=10;
bij_mc.links_mc.stop();
bij_mc.rechts_mc.play();
bij_mc.rotation = -5;
} else if (evt.keyCode==Keyboard.RIGHT) {
bij_mc.links_mc.x +=10;
bij_mc.rechts_mc.x +=10;
bij_mc.lichaam_mc.x += 10;
bij_mc.links_mc.play();
bij_mc.rechts_mc.stop();
bij_mc.rotation = 5;
} else if (evt.keyCode==Keyboard.UP) {
bij_mc.links_mc.y -=10;
bij_mc.rechts_mc.y -= 10;
bij_mc.lichaam_mc.y -= 10;
bij_mc.links_mc.play();
bij_mc.rechts_mc.play();
bij_mc.rotation = 0;
} else if (evt.keyCode==Keyboard.DOWN) {
bij_mc.links_mc.y +=10;
bij_mc.rechts_mc.y += 10;
bij_mc.lichaam_mc.y += 10;
bij_mc.links_mc.stop();
bij_mc.rechts_mc.stop();
bij_mc.rotation = 0;
}
}
function stopbeweeg(evt:KeyboardEvent):void {
bij_mc.links_mc.play();
bij_mc.rechts_mc.play();
bij_mc.rotation = 0;
}

Answer 1

stage.addEventListener(Event.ENTER_FRAME, onEnterFrame);
private function onEnterFrame(event:Event):void
{
// update beweeg
checkBoundaries()
}
private function checkBoundaries():void
{
// left
if (bij_mc.x < 0)
bij_mc.x = 0;
// right
else if (bij_mc.x > stage.stageWidth)
bij_mc.x = stage.stageWidth - bij_mc.width;
// top
if (bij_mc.y < 0)
bij_mc.y = 0;
// bottom
else if (bij_mc.y > stage.stageHeight)
bij_mc.y = stage.stageHeight - bij_mc.height;
}
Update each movie clip accordingly.