code: def test_multichannel(self):
      num_channels = 3
      samples = np.random.normal(
          0, 0.1, size=(num_channels, 5555)
      ).astype(np.float32)
      sample_rate = 16000
      augmenter = TimeStretch(
          min_rate=0.8, max_rate=0.9, leave_length_unchanged=True, p=1.0
      )
  
      samples_out = augmenter(samples=samples, sample_rate=sample_rate)
  
      assert samples.dtype == samples_out.dtype
      assert samples.shape == samples_out.shape
      for i in range(num_channels):
          assert not np.allclose(samples[i], samples_out[i])
  
imports: import numpy
  from audiomentations import TimeStretch
label_desc: Use image node_id 3 for calling the TestTimeStretch obj's underlying member method code with example usage: obj.test_multichannel() without return types