IllegalOperationError  - AS3

package {
    import flash.display.DisplayObject;
    import flash.display.Sprite;
    import flash.errors.IllegalOperationError;

    public class IllegalOperationErrorExample extends Sprite {
        public function IllegalOperationErrorExample() {
            var child:Sprite = new Sprite();
            try {
                addChild(child);
            }
            catch(e:IllegalOperationError) {
                trace(e);
            }
        }

        public override function addChild(child:DisplayObject):DisplayObject {
            throw new IllegalOperationError("addChild cannot be performed on the IllegalOperationErrorExample class");
        }
    }
}