Return a json dictionary representing this model.

def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'location') and self.location is not None:
            _dict['location'] = self.location._to_dict()
        if hasattr(self, 'text') and self.text is not None:
            _dict['text'] = self.text
        if hasattr(self, 'section_title') and self.section_title is not None:
            _dict['section_title'] = self.section_title._to_dict()
        if hasattr(self, 'table_headers') and self.table_headers is not None:
            _dict['table_headers'] = [x._to_dict() for x in self.table_headers]
        if hasattr(self, 'row_headers') and self.row_headers is not None:
            _dict['row_headers'] = [x._to_dict() for x in self.row_headers]
        if hasattr(self, 'column_headers') and self.column_headers is not None:
            _dict['column_headers'] = [
                x._to_dict() for x in self.column_headers
            ]
        if hasattr(self,
                   'key_value_pairs') and self.key_value_pairs is not None:
            _dict['key_value_pairs'] = [
                x._to_dict() for x in self.key_value_pairs
            ]
        if hasattr(self, 'body_cells') and self.body_cells is not None:
            _dict['body_cells'] = [x._to_dict() for x in self.body_cells]
        return _dict