How to animate what you draw on the stage with Actionscript 3.0

Hi,

I have been practicing on how to draw shapes on the stage with actionscript and it seems fun.

var rec:Sprite = new Sprite();
with (rec.graphics) {

	beginFill(0xff23564,1);
	lineStyle(0);	
	drawCircle(20,20,50);
	moveTo(100, 100);
	lineTo(100,0);
	lineTo(200, 0);
	lineTo(200, 100);
	lineTo(100, 100);
	endFill();
	
}

addChild(rec);

But now I was wondering how hard would it be to animate what you draw for instance how would you animate a simple line?

var rec:Sprite = new Sprite();
with (rec.graphics) {
	lineStyle(0);	
	moveTo(100, 100);
	lineTo(100,0);
	endFill();	
}

addChild(rec);

Thanks