public class @ax-sample-flex-burn-vu extends Sprite {
  
                  // the rate at which the flames should move
                  private static const FLICKER_RATE:Number = 10;
  
                  private var _blackField:TextField;
                  private var _flame:BitmapData;
                  private var _perlinNoise:BitmapData;
                  private var _perlinOffsets:Array;
                  private var _perlinSeed:int;