private async Task <WeatherInfoCollection> performMergeTypeImportAsync( WeatherInfoCollection newWeatherInfoCollection) { var matchedDates = newWeatherInfoCollection.Where(weatherInfo => ActiveWeatherInfoCollection.Active.Any(activeWeatherInfo => activeWeatherInfo.Date == weatherInfo.Date)); var unmatchedDates = newWeatherInfoCollection.Where(weatherInfo => ActiveWeatherInfoCollection.Active.All(activeWeatherInfo => activeWeatherInfo.Date != weatherInfo.Date)); await this.requestUserMergePreference(matchedDates); foreach (var current in unmatchedDates) { ActiveWeatherInfoCollection.Active.Add(current); } return(ActiveWeatherInfoCollection.Active); }