code: def test_values(self):
      data = np.arange(20).reshape(10, 2) * 2
      correct = np.tile([-2, 0], 10).reshape(10, 2)
      self.assertTrue(np.allclose(correct, local_group_delay(data)))
      data = np.arange(20).reshape(10, 2) * 4
      correct = np.tile([2.28318531, 0], 10).reshape(10, 2)
      self.assertTrue(np.allclose(correct, local_group_delay(data)))
  
imports: from __future__ import absolute_import, division, print_function
  import sys
  import unittest
  from os.path import join
  from madmom.audio.spectrogram import Spectrogram
  from madmom.audio.stft import *
  from .None import AUDIO_PATH
label_desc: Use image node_id 2 for calling the TestLocalGroupDelayFunction obj's underlying member method code with example usage: obj.test_values() without return types