code: def test_InsertInBackground(self):
      random_generator = np.random.default_rng(1)
      self.evaluate_class(
          audaugs.InsertInBackground(
              offset_factor=0.3, seed=random_generator
          ),
          fname="insert_in_background2",
      )
  
imports: import json
  import random
  import unittest
  import numpy
  from augly import audio
  from augly.tests.audio_tests.base_unit_test import BaseAudioUnitTest
  from augly.utils import AUDIO_METADATA_PATH
label_desc: Use image node_id 11 for calling the TransformsAudioUnitTest obj's underlying member method code with example usage: obj.test_InsertInBackground() without return types