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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def results(self, key):
 """Serves a key off of the results backend"""

        if not results_backend:
            return json_error_response("Results backend isn't configured")

        read_from_results_backend_start = now_as_float()
        blob = results_backend.get(key)
        stats_logger.timing(
            'sqllab.query.results_backend_read',
            now_as_float() - read_from_results_backend_start,
        )
        if not blob:
            return json_error_response(
                'Data could not be retrieved. '
                'You may want to re-run the query.',
                status=410,
            )

        query = db.session.query(Query).filter_by(results_key=key).one()
        rejected_tables = security_manager.rejected_datasources(
            query.sql, query.database, query.schema)
        if rejected_tables:
            return json_error_response(security_manager.get_table_access_error_msg(
                '{}'.format(rejected_tables)), status=403)

        payload = utils.zlib_decompress_to_string(blob)
        display_limit = app.config.get('DEFAULT_SQLLAB_LIMIT', None)
        if display_limit:
            payload_json = json.loads(payload)
            payload_json['data'] = payload_json['data'][:display_limit]
        return json_success(
            json.dumps(
                payload_json,
                default=utils.json_iso_dttm_ser,
                ignore_nan=True,
            ),
        )