def populate_class_members(self, element_cls, prop_name):
        """
        Add the appropriate methods to *element_cls*.
        """
        super(ZeroOrOne, self).populate_class_members(element_cls, prop_name)
        self._add_getter()
        self._add_creator()
        self._add_inserter()
        self._add_adder()
        self._add_get_or_adder()
        self._add_remover()