class_docstr: The low-level interface dataset class
  
  Args:
      path_prefix (str): The index (.idx) and data (.bin) prefix
  
      multimodal (bool, optional): Whether the dataset is multimodal. Defaults to False.
class_docstr_tok: ["The","low-level","interface","dataset","class","Args",":","path_prefix","(","str",")",":","The","index","(",".idx",")","and","data","(",".bin",")","prefix","multimodal","(","bool",",","optional",")",":","Whether","the","dataset","is","multimodal",".","Defaults","to","False","."]
docstr: Retrieve a single item from the dataset with the option to only
  return a portion of the item.
  
  get(idx) is the same as [idx] but get() does not support slicing.
docstr_tok: ["Retrieve","a","single","item","from","the","dataset","with","the","option","to","only","return","a","portion","of","the","item",".","get","(","idx",")","is","the","same","as","[","idx","]","but","get","(",")","does","not","support","slicing","."]
code: def get(
      self, idx: int, offset: int = 0, length: Optional[int] = None
  ) -> numpy.ndarray:
      """Retrieve a single item from the dataset with the option to only
      return a portion of the item.
  
      get(idx) is the same as [idx] but get() does not support slicing.
      """
      sequence_pointer, sequence_length, sequence_mode = self.index[idx]
      if length is None:
          length = sequence_length - offset
      sequence_pointer += offset * DType.size(self.index.dtype)
      sequence = numpy.frombuffer(
          self.bin_buffer,
          dtype=self.index.dtype,
          count=length,
          offset=sequence_pointer,
      )
      return (
          (sequence, sequence_mode)
          if sequence_mode is not None
          else sequence
      )
  
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 8 for calling the MMapIndexedDataset obj's underlying member method code with example usage: obj.get(idx, offset, length) and returns: unknown