         
     }
     
-    func sortByDistance(center: CLLocationCoordinate2D, ascending: Bool, latitudeKey: String = "lat", longitudeKey: String = "lng") -> [T] {
+    func sortByDistance(center: CLLocationCoordinate2D, ascending: Bool, latitudeKey: String = "lat", longitudeKey: String = "lng") -> [Element] {
         
         return self
             .addDistance(center: center, latitudeKey: latitudeKey, longitudeKey: longitudeKey)

     
     - returns: Filtered objects inside MKCoordinateRegion
     */
    func filterGeoRegion(region: MKCoordinateRegion, latitudeKey: String = "lat", longitudeKey: String = "lng") -> Results<T> {
        
        let box = region.geoBox
        

}

// MARK: - Private core extensions
private extension Results where Element: Object {
    
    /**
     Add distance to sort results
