public IObservable <IReadOnlyList <YoutubeSong> > GetSongsAsync(string searchTerm = null)
{
searchTerm = searchTerm ?? string.Empty;
return(Observable.Defer(() => requestCache.GetOrFetchObject(BlobCacheKeys.GetKeyForYoutubeCache(searchTerm),
() => RealSearch(searchTerm), DateTimeOffset.Now + CacheDuration)));
}
