code: def __len__(self):
      return len(self._walker)
  
file_path: audio/examples/dnn_beamformer/datamodule.py
imports: from pathlib import Path
  from typing import Tuple, Union
  import lightning.pytorch
  import torch
  import torchaudio
  from torch import Tensor
  from torch.utils.data import Dataset
  from utils import CollateFnL3DAS22
label_desc: Use image node_id 2 for calling the L3DAS22 obj's underlying member method code with example usage: obj.__len__() and returns: len