code: def _valid_collate_fn(self, samples: List):
      features, feature_lengths = self._valid_extract_features(samples)
      targets, target_lengths = self._extract_labels(samples)
      return Batch(features, feature_lengths, targets, target_lengths)
  
imports: import os
  from functools import partial
  from typing import List
  import sentencepiece
  import torch
  import torchaudio
  from common import Batch, batch_by_token_count, FunctionalModule, GlobalStatsNormalization, piecewise_linear_log, post_process_hypos, spectrogram_transform, WarmupLR
  from pytorch_lightning import LightningModule
  from torchaudio.models import emformer_rnnt_base, RNNTBeamSearch
label_desc: Use image node_id 6 for calling the TEDLIUM3RNNTModule obj's underlying member method code with example usage: obj._valid_collate_fn(samples) and returns: Batch