 }
 
 // MARK: - Dictionary
+
 extension JSON {
     
     private func _map<Key:Hashable ,Value, NewValue>(source: [Key: Value], transform: Value -> NewValue) -> [Key: NewValue] {

        }
    }
    
    public subscript(path: SubscriptType...) -> JSON {
        get {
            return self[path]

        }
    }

    /// If `type` is `.Dictionary`, return json which's object is `dictionary[key]` , otherwise return null json with error.
    private subscript(#key: String) -> JSON {
        get {
            var returnJSON = JSON.nullJSON
