code: def test_types(self):
      result = LocalGroupDelay(sample_file)
      self.assertIsInstance(result, LocalGroupDelay)
      self.assertIsInstance(result, np.ndarray)
      # attributes
      self.assertIsInstance(result.phase, Phase)
      self.assertIsInstance(result.stft, ShortTimeFourierTransform)
      self.assertIsInstance(result.bin_frequencies, np.ndarray)
      # properties
      self.assertIsInstance(result.num_bins, int)
      self.assertIsInstance(result.num_frames, int)
  
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 1 for calling the LocalGroupDelayClass obj's underlying member method code with example usage: obj.test_types() without return types