code: def test_normalize_all_zeros(self):
      samples = np.array([0.0, 0.0, 0.0, 0.0], dtype=np.float32)
      sample_rate = 16000
      augmenter = Normalize(p=1.0)
      samples = augmenter(samples=samples, sample_rate=sample_rate)
  
      assert np.amin(samples) == 0.0
      assert samples[-1] == 0.0
      assert samples.dtype == np.float32
      assert samples.shape[-1] == 4
  
file_path: audiomentations/tests/test_normalize.py
imports: import numpy
  from numpy.testing import assert_array_equal
  from audiomentations import Normalize
label_desc: Use image node_id 3 for calling the TestNormalize obj's underlying member method code with example usage: obj.test_normalize_all_zeros() without return types