function setSongVisualization(songIndex, visualizationKey) {
    if (_config2.default.songs[songIndex]) {
      if (_config2.default.visualizations.available[visualizationKey] != undefined) {
        _config2.default.songs[songIndex].visualization = visualizationKey;
      } else {
        _debug2.default.writeMessage("A visualization does not exist for the key provided.");
      }
    } else {
      _debug2.default.writeMessage("A song at that index is undefined");
    }
  }
Set a visualization for the song.

@param {number} songIndex - The index of the song in the songs array we are setting the visualization for.
@param {string} visualizationKey - The key of the visualization we are adding to the playlist.