code: def test_types(self):
      self.assertIsInstance(self.result, Signal)
      self.assertIsInstance(self.result, np.ndarray)
      self.assertTrue(self.result.dtype == np.int16)
      self.assertTrue(type(self.result.sample_rate) == int)
  
imports: from __future__ import absolute_import, division, print_function
  import io
  import unittest
  from os.path import join
  from madmom.io.audio import *
  from .None import AUDIO_PATH, DATA_PATH
label_desc: Use image node_id 2 for calling the TestWriteWaveFileFunction obj's underlying member method code with example usage: obj.test_types() without return types