anchor.diff:  
   
     void toggleSound(Event e) {
  -    ImageElement image = toggleSoundButton.children.first;
       if(isPlaying) {
  -      image.src = "img/note.svg";
  -      isPlaying = false;
  -      setVolume(0.0);
  +      pause();
       }
       else {
  -      image.src = "img/rest.svg";
  -      isPlaying = true;
  -      setVolume(volumeSlider.value);
  +      play();
       }
  +  }
  +
  +  void play() {
  +    toggleSoundImage.src = "img/rest.svg";
  +    isPlaying = true;
  +    setVolume(volumeSlider.value);
  +  }
  +
  +  void pause() {
  +    toggleSoundImage.src = "img/note.svg";
  +    isPlaying = false;
  +    setVolume(0.0);
     }
   
     void setVolume(double vol) {
  
positive.code:   RangeSlider volumeSlider;
    bool isPlaying;
    AudioElement stream;
  
    MediaBar.created()
      : super.created() {
  
negative.code:     getShadowRoot("media-bar").applyAuthorStyles = true;
  
      toggleSoundButton = $["toggleSound"];
      toggleSoundImage = toggleSoundButton.children.first;
      volumeSlider = new RangeSlider($["volumeSlider"]);
      stream = $["audioElement"];
  
  