class_docstr: *LibriSpeech* :cite:`7178964` dataset.
  
  Args:
      root (str or Path): Path to the directory where the dataset is found or downloaded.
      url (str, optional): The URL to download the dataset from,
          or the type of the dataset to dowload.
          Allowed type values are ``"dev-clean"``, ``"dev-other"``, ``"test-clean"``,
          ``"test-other"``, ``"train-clean-100"``, ``"train-clean-360"`` and
          ``"train-other-500"``. (default: ``"train-clean-100"``)
      folder_in_archive (str, optional):
          The top-level directory of the dataset. (default: ``"LibriSpeech"``)
      download (bool, optional):
          Whether to download the dataset if it is not found at root path. (default: ``False``).
class_docstr_tok: ["*","LibriSpeech","*",":","cite",":","`","7178964","`","dataset",".","Args",":","root","(","str","or","Path",")",":","Path","to","the","directory","where","the","dataset","is","found","or","downloaded",".","url","(","str",",","optional",")",":","The","URL","to","download","the","dataset","from",",","or","the","type","of","the","dataset","to","dowload",".","Allowed","type","values","are","``","``","dev-clean","''","``",",","``","``","dev-other","''","``",",","``","``","test-clean","''","``",",","``","``","test-other","''","``",",","``","``","train-clean-100","''","``",",","``","``","train-clean-360","''","``","and","``","``","train-other-500","''","``",".","(","default",":","``","``","train-clean-100","''","``",")","folder_in_archive","(","str",",","optional",")",":","The","top-level","directory","of","the","dataset",".","(","default",":","``","``","LibriSpeech","''","``",")","download","(","bool",",","optional",")",":","Whether","to","download","the","dataset","if","it","is","not","found","at","root","path",".","(","default",":","``","False","``",")","."]
code: def __len__(self) -> int:
      return len(self._walker)
  
file_path: audio/src/torchaudio/datasets/librispeech.py
imports: import os
  from pathlib import Path
  from typing import Tuple, Union
  from torch import Tensor
  from torch.utils.data import Dataset
  from torchaudio._internal import download_url_to_file
  from torchaudio.datasets.utils import _extract_tar, _load_waveform
label_desc: Use image node_id 4 for calling the LIBRISPEECH obj's underlying member method code with example usage: obj.__len__() and returns: len