code: public void play(SoundCloudTrack track) {
          checkState();
          ArrayList<SoundCloudTrack> tracks = mPlayerPlaylist.getPlaylist().getTracks();
          int position = tracks.indexOf(track);
          if (position > -1) {
              mPlayerPlaylist.setPlayingTrack(position);
              PlaybackService.play(getContext(), mClientKey, track);
          }
      }
docs: Play a track which have been added to the player playlist.
  <p/>
  See also {@link CheerleaderPlayer#addTrack(SoundCloudTrack)}
  {@link CheerleaderPlayer#addTracks(List)}
  
  @param track the track to play.