public BoroughViewModel(Borough borough, CityViewModel parentCity)
     : base(parentCity, true)
 {
     _entity = borough;
 }
 public CityGroupViewModel(string name, CityViewModel parentCity)
     : base(parentCity, true)
 {
     this.Name = name;
     _parent   = parentCity;
 }
 public StreetViewModel(Street street, CityViewModel parentCity)
     : base(parentCity, false)
 {
     _entity = street;
 }