code: def extractSources(self, samples, sources):
      sources = (
          ["bass", "drums", "other", "vocals"]
          if not sources
          else sources
      )
      return torch.stack(
          [samples[seed_dict[source]][0] for source in sources]
      )
  
file_path: audio/test/torchaudio_unittest/datasets/musdb_hq_test.py
imports: import os
  import torch
  from parameterized import parameterized
  from torchaudio.datasets import musdb_hq
  from torchaudio.datasets.musdb_hq import _VALIDATION_SET
  from torchaudio_unittest.common_utils import get_whitenoise, save_wav, TempDirMixin, TorchaudioTestCase
label_desc: Use image node_id 7 for calling the TestMusDB_HQ obj's underlying member method code with example usage: obj.extractSources(samples, sources) and returns: torch