code: public void addTrack(SoundCloudTrack track, boolean playNow) {
          checkState();
          mPlayerPlaylist.add(track);
          for (CheerleaderPlaylistListener listener : mCheerleaderPlaylistListeners) {
              listener.onTrackAdded(track);
          }
          if (playNow) {
              play(mPlayerPlaylist.size() - 1);
          }
      }
docs: Add a track to the current SoundCloud player playlist.
  
  @param track   {@link fr.tvbarthel.cheerleader.library.client.SoundCloudTrack} to be
  added to the player.
  @param playNow true to play the track immediately.