 
     /**
      Returns bindable sink wich deletes objects in sequence from Realm.
+
      - parameter: onError - closure to implement custom error handling
      - returns: `AnyObserver<O>`, which you can use to subscribe an `Observable` to
      */

     - parameter: onError - closure to implement custom error handling
     - returns: `AnyObserver<S>`, which you can use to subscribe an `Observable` to
     */
    public func add<S: Sequence>(update: Bool = false,
                    onError: ((S?, Error)->Void)? = nil) -> AnyObserver<S> where S.Iterator.Element: Object {
        return RealmObserver(realm: base) {realm, elements, error in
            guard let realm = realm else {
                onError?(nil, error ?? RxRealmError.unknown)
                return


            return Disposables.create {
                token.stop()
            }
        }
    }
