docstr: Returns the rank of the writer.
docstr_tok: ["Returns","the","rank","of","the","writer","."]
code: def rank(self) -> int:
      """Returns the rank of the writer."""
      if self._rank is None:
          rank = os.getenv("DATA_OPTIMIZER_GLOBAL_RANK", None)
          if rank:
              self._rank = int(rank)
          else:
              self._worker_env = _WorkerEnv.detect()
              self._rank = (
                  self._distributed_env.global_rank
                  * self._worker_env.world_size
                  + self._worker_env.rank
              )
      return self._rank
  
imports: import json
  import os
  import warnings
  from dataclasses import dataclass
  from time import sleep
  from typing import Any, Dict, List, Optional, Tuple, Union
  import numpy
  import torch
  from lightning.data.streaming.compression import _COMPRESSORS, Compressor
  from lightning.data.streaming.constants import _INDEX_FILENAME, _TORCH_GREATER_EQUAL_2_1_0
  from lightning.data.streaming.serializers import Serializer, _get_serializers
  from lightning.data.utilities.env import _DistributedEnv, _WorkerEnv
  from lightning.data.utilities.format import _convert_bytes_to_int, _human_readable_bytes
label_desc: Use image node_id 3 for calling the BinaryWriter obj's underlying member method code with example usage: obj.rank() and returns: self