code: def test_invert_channels(self):
      self.evaluate_function(audaugs.invert_channels)
  
imports: import unittest
  from augly import audio
  from augly.tests.audio_tests.base_unit_test import BaseAudioUnitTest
label_desc: Use image node_id 9 for calling the FunctionalAudioUnitTest obj's underlying member method code with example usage: obj.test_invert_channels() without return types