code: def test_insert_in_background(self):
      self.evaluate_function(
          audaugs.insert_in_background, offset_factor=0.3
      )
  
imports: import unittest
  from augly import audio
  from augly.tests.audio_tests.base_unit_test import BaseAudioUnitTest
label_desc: Use image node_id 8 for calling the FunctionalAudioUnitTest obj's underlying member method code with example usage: obj.test_insert_in_background() without return types