public override void FindProperties(PropertyDataSource dataSource,
 int pageNumber, Action<PropertyDataSourceResult> callback, Action<Exception> error)
   {
       dataSource.FindProperties(SearchText, pageNumber, callback, error);
   }
   public override void FindProperties(PropertyDataSource dataSource,
 int pageNumber, Action<PropertyDataSourceResult> callback, Action<Exception> error)
   {
       dataSource.FindProperties(Location.Latitude, Location.Longitude, pageNumber, callback, error);
   }