private static async Task<IEnumerable<ILeague>> RetrievesLeaguesDataAsync( IApiModel leagueModel, long summonerId, RegionEnum? region = null) { if (leagueModel == null) throw new ArgumentNullException("leagueModel"); var leagueService = new LeagueService(leagueModel.ApiConfiguration); return await leagueService.RetrievesLeaguesDataForSummonerAsync(summonerId, region); }