code: def get_mock_dataset(dataset_dir: str):
      os.makedirs(dataset_dir, exist_ok=True)
  
      all_samples = []
      script_samples = []
      impro_samples = []
      for session in range(1, 4):
          samples = _get_samples(dataset_dir, session)
          all_samples += samples[0]
          script_samples += samples[1]
          impro_samples += samples[2]
      return all_samples, script_samples, impro_samples
  
file_path: audio/test/torchaudio_unittest/datasets/iemocap_test.py
imports: import os
  import random
  from torchaudio.datasets import iemocap
  from torchaudio_unittest.common_utils import get_whitenoise, save_wav, TempDirMixin, TorchaudioTestCase
label_desc: Use image node_id 4 for calling a global function with example usage: get_mock_dataset(dataset_dir) and returns: all_samples,  script_samples,  impro_samples