def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
def set_submodule(self, submodule: 'Submodule') -> None:
        """Set this instance's submodule. It must be called before
        the first write operation begins"""
        self._smref = weakref.ref(submodule)