private void ChangeCity(int?cityId)
 {
     StreetList.Clear();
     if (!cityId.HasValue)
     {
         return;
     }
     foreach (var street in _requestService.GetStreets(cityId.Value).OrderBy(s => s.Name))
     {
         StreetList.Add(street);
     }
     OnPropertyChanged(nameof(StreetList));
 }