public static Song CreateOrLoadSong(IRepository<Song> songs, SongDetails songDetails)
        {
            Song song = songs.Get(songDetails.ID);
            if (song != null)
            {
                return song;
            }

            Song newSong = new Song()
            {
                Title = songDetails.Title,
                Genre = songDetails.Genre,
                Year = songDetails.Year
            };

            songs.Add(newSong);

            return newSong;
        }
        private static SongDetails ConvertToSongDetails(SongModel songModel)
        {
            SongDetails songDetails = new SongDetails()
            {
                ID = songModel.ID,
                Title = songModel.Title,
                Genre = songModel.Genre,
                Year = songModel.Year
            };

            return songDetails;
        }