package  {
	import flash.display.MovieClip;
	import flash.events.*;

	public class enemy extends MovieClip {
		private var _root: Object;
		var speed: int = 3;

		public function enemy() {
			// constructor code
			addEventListener(Event.ADDED, beginClass);
		}

		private function beginClass(e: Event): void {
			_root = MovieClip(root);
			stage.addEventListener(Event.ENTER_FRAME, moveRobot);
		}

		private function moveRobot (e: Event): void {
				y += speed;

				//code to stop going off screen
			if ((this.y - (this.height / 2)) < 0) {
				speed *= -1;
			}

			if ((this.y + (this.height / 2)) > 400) {
				speed *= -1;
			}
		}
	}
}