code: def test_to_mono_intensity(self):
      intensity = audaugs.to_mono_intensity(
          metadata={"src_num_channels": 1}
      )
      self.assertAlmostEqual(intensity, 0.0)
  
imports: import unittest
  import numpy
  from augly import audio
label_desc: Use image node_id 20 for calling the IntensityAudioUnitTest obj's underlying member method code with example usage: obj.test_to_mono_intensity() without return types