code: def from_pb(cls, operation_pb, client, **caller_metadata):
          
          result = cls(operation_pb.name, client, **caller_metadata)
          result._update_state(operation_pb)
          result._from_grpc = True
          return result
docs: Factory:  construct an instance from a protobuf.
  
          :type operation_pb:
              :class:`~google.longrunning.operations_pb2.Operation`
          :param operation_pb: Protobuf to be parsed.
  
          :type client: object: must provide ``_operations_stub`` accessor.
          :param client: The client used to poll for the status of the operation.
  
          :type caller_metadata: dict
          :param caller_metadata: caller-assigned metadata about the operation
  
          :rtype: :class:`Operation`
          :returns: new instance, with attributes based on the protobuf.