code: def test_stack_tensors_3d(self):
      tensors = [torch.ones([2, 2]), torch.ones([1, 3])]
      max_lens = [4, 2]
      expected_output = torch.tensor(
          [[[1, 1, 0, 0], [1, 1, 0, 0]], [[1, 1, 1, 0], [0, 0, 0, 0]]],
          dtype=torch.float32,
      )
  
      stacked_tensor = stack_tensors(tensors=tensors, max_lens=max_lens)
  
      torch.testing.assert_close(stacked_tensor, expected_output)
  
imports: from pathlib import Path
  import librosa
  import numpy
  import pytest
  import torch
  from nemo.collections.tts.parts.utils.tts_dataset_utils import filter_dataset_by_duration, get_abs_rel_paths, get_audio_filepaths, load_audio, normalize_volume, stack_tensors
label_desc: Use image node_id 14 for calling the TestTTSDatasetUtils obj's underlying member method code with example usage: obj.test_stack_tensors_3d() without return types