contructor
Constructor. This creates textfields and sets up the flame and noise properties that will be used in the flame animation. Finally, the handler for the animation is set up. 

  
                  public function @ax-sample-flex-burn-vu() {
                          makeFlame();
                          makeFields();
                          makeNoise();
                          addEventListener(Event.ENTER_FRAME, onSpriteEnterFrame);
                  }