public async Task Execute( [Summary("The Imgur account ID of the Registered User to search for.")] int UserID ) { Log.Application_.LogVerbose("Executing UserTaglists for user ID '{0:D}'", UserID); IReadOnlyCollection <Taglist> AllTaglists = await ReadAllTaglistsAndUsers(); if (AllTaglists is null) { return; } ICollection <Taglist> Result = ( from TL in AllTaglists where TL.hasRegisteredUser(UserID) select TL ).ToList(); await DisplayResults( Result, string.Format("Taglists that user ID '{0:D}' appears in:", UserID) ); }