private void OnSongUpdated(SongAddAndDetailViewModel source, Song song)
        {
            var songInList = Songs.Single(s => s.Id == song.Id);

            songInList.Id     = song.Id;
            songInList.Artist = song.Artist;
            songInList.Title  = song.Title;
            songInList.Text   = song.Text;
            songInList.Chords = song.Chords;
        }
 private void OnSongDeleted(SongAddAndDetailViewModel source, Song song)
 {
     Songs.Remove(Songs.Where(s => s.Id == song.Id).Single());
     OnPropertyChanged(nameof(Songs));
 }
 private void OnSongAdded(SongAddAndDetailViewModel source, Song song)
 {
     Songs.Add(new SongViewModel(song));
 }