code: def _is_master(self):
      return (
          self._world_size <= 1 or self._local_rank == self._master_rank
      )
  
imports: import logging
  import numpy
  import torch
  import torch.distributed
  from transformers.training_args import TrainingArguments
  from fate.ml.aggregator import AggregatorType, aggregator_map
label_desc: Use image node_id 4 for calling the AggregatorClientWrapper obj's underlying member method code with example usage: obj._is_master() and returns: unknown