code: def key(self) -> str:
      return self.value
  
imports: import json
  import time
  from enum import Enum
  from logging import getLogger
  from typing import Dict, List, Any
  import grpc
  import numpy
  from fate.arch.federation.backends.osx import osx_pb2
  from fate.arch.federation.backends.osx.osx_pb2_grpc import PrivateTransferTransportStub
label_desc: Use image node_id 1 for calling the Metadata obj's underlying member method code with example usage: obj.key() and returns: self