private async Task <SmartPlaylistDto[]> GetAllCachedSmartPlaylistAsync()
 {
     return((await _memCache.GetOrCreateManyAsync(async() =>
     {
         return (await _decorated.GetAllSmartPlaylistsAsync()
                 .ConfigureAwait(false))
         .ToDictionary(x => (object)x.Id, y => (object)y);
     }, Const.GetAllSmartPlaylistsCacheExpiration).ConfigureAwait(false))
            .OfType <SmartPlaylistDto>()
            .ToArray());
 }