class_docstr: Object class to write the index (.idx) file
  
  Args:
      idx_path (str): The path to the index file
  
      dtype (Type[numpy.number]): The dtype of the index file
class_docstr_tok: ["Object","class","to","write","the","index","(",".idx",")","file","Args",":","idx_path","(","str",")",":","The","path","to","the","index","file","dtype","(","Type","[","numpy.number","]",")",":","The","dtype","of","the","index","file"]
code: def __init__(self, idx_path: str, dtype: Type[numpy.number]) -> None:
      self.idx_path = idx_path
      self.dtype = dtype
  
imports: import logging
  import os
  import shutil
  import struct
  import time
  from enum import Enum
  from functools import lru_cache
  from itertools import accumulate
  from types import TracebackType
  from typing import List, Optional, Tuple, Type, Union
  import numpy
  import torch
  from megatron.core.datasets.utils import log_single_rank
label_desc: Use image node_id 1 to create a new _IndexWriter object from inherited base classes: object with example: obj = _IndexWriter(idx_path, dtype)