code: def test_methods(self):
      result = ShortTimeFourierTransform(sample_file)
      self.assertIsInstance(result.spec(), Spectrogram)
      self.assertIsInstance(result.phase(), Phase)
  
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 3 for calling the ShortTimeFourierTransformClass obj's underlying member method code with example usage: obj.test_methods() without return types