class_docstr: Object class to read the index (.idx) file
  
  Args:
      idx_path (str): The path to the index file
  
      multimodal (bool): Whether the dataset is multimodal
class_docstr_tok: ["Object","class","to","read","the","index","(",".idx",")","file","Args",":","idx_path","(","str",")",":","The","path","to","the","index","file","multimodal","(","bool",")",":","Whether","the","dataset","is","multimodal"]
docstr: Return the pointer, length, and mode at the index
  
  Args:
      idx (int): The index into the dataset
  
  Returns:
      Tuple[numpy.int32, numpy.int64, Optional[numpy.int8]]: The pointer, length and mode at
      the index
docstr_tok: ["Return","the","pointer",",","length",",","and","mode","at","the","index","Args",":","idx","(","int",")",":","The","index","into","the","dataset","Returns",":","Tuple","[","numpy.int32",",","numpy.int64",",","Optional","[","numpy.int8","]","]",":","The","pointer",",","length","and","mode","at","the","index"]
code: def __getitem__(
      self, idx: int
  ) -> Tuple[numpy.int32, numpy.int64, Optional[numpy.int8]]:
      """Return the pointer, length, and mode at the index
  
      Args:
          idx (int): The index into the dataset
  
      Returns:
          Tuple[numpy.int32, numpy.int64, Optional[numpy.int8]]: The pointer, length and mode at
          the index
      """
      return (
          self.sequence_pointers[idx],
          self.sequence_lengths[idx],
          self.sequence_modes[idx]
          if self.sequence_modes is not None
          else None,
      )
  
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 4 for calling the _IndexReader obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self,  self,  unknown