public PlaylistApiController(ILogger <HomeController> logger, IPlaylistBuilder playlistBuilder,
                              IAppConfig appConfig)
 {
     _logger          = logger ?? throw new ArgumentNullException(nameof(logger));
     _playlistBuilder = playlistBuilder ?? throw new ArgumentNullException(nameof(playlistBuilder));
     _appConfig       = appConfig ?? throw new ArgumentNullException(nameof(appConfig));
 }
        internal PlaylistGenerator(PlaylistGeneratorSettings settings, 
			IPlaylistRepository playlistRepository = null, 
			IPlaylistBuilder playlistBuilder = null, 
			IPlaylistRenderer playlistRenderer = null)
        {
            Settings = settings;

            _playlistConfigurationRepository = playlistRepository ?? new PlaylistConfigurationRepository();
            _playlistBuilder = playlistBuilder ?? new PlaylistCreator();
            _playlistRenderer = playlistRenderer ?? new PlaylistRenderer();
        }