Inserts default values from :attr:`StructuredDictMixin.structure`
        to `self` by merging the two structures
        (see :func:`monk.manipulation.merge_defaults`).

def _insert_defaults(self):
        """ Inserts default values from :attr:`StructuredDictMixin.structure`
        to `self` by merging the two structures
        (see :func:`monk.manipulation.merge_defaults`).
        """
        merged = merge_defaults(self.structure, self)
        self.update(merged)