def patch_instance(self, body, instance, project_id=None):
        """
        
        """
        response = self.get_conn().instances().patch(
            project=project_id,
            instance=instance,
            body=body
        ).execute(num_retries=self.num_retries)
        operation_name = response["name"]
        self._wait_for_operation_to_complete(project_id=project_id,
                                             operation_name=operation_name)