code: def add(*items)
        notify_will_change! if items.count > 0
        items.flatten.parse_objects.each do |item|
          collection.push(item) if item.is_a?(Parse::Pointer)
        end
        @collection
      end
docs: Add Parse::Objects to the collection.
   @overload add(parse_object)
    Add a Parse::Object or Parse::Pointer to this collection.
    @param parse_object [Parse::Object,Parse::Pointer] the object to add
   @overload add(parse_objects)
    Add an array of Parse::Objects or Parse::Pointers to this collection.
    @param parse_objects [Array<Parse::Object,Parse::Pointer>] the array to append.
   @return [Array<Parse::Object>] the collection