Prototype?

1

Hi, i was checking the code for the resizable gallery that’s on “best of k”, and i found this code:


MovieClip.prototype.loadPic = function(pic){
	_root.containerMC._alpha = 0;
	this.loadMovie(pic);
	_root.onEnterFrame = function(){
		var t = containerMC.getBytesTotal(), l = containerMC.getBytesLoaded();
		if (t != 0 && Math.round(l/t) == 1){
			var w = containerMC._width + spacing, h = containerMC._height + spacing;
			border.resizeMe(w, h);
			delete _root.onEnterFrame;
		}
	}
};

i’m “returning” to flash, after a year, almost two, so i dont remember that “prototype” function…

so, can someone plz explain it to me ??? :S what is it for? is it used instead of something else?..