code: def test_channel(inceptionv1):
      objective = objectives.channel("mixed4a_pre_relu", 42)
      assert_gradient_ascent(objective, inceptionv1)
  
imports: from __future__ import absolute_import, division, print_function
  import pytest
  import tensorflow
  import numpy
  from lucid.optvis import objectives, param, render, transform
  from lucid.modelzoo.vision_models import InceptionV1
label_desc: Use image node_id 4 for calling a global function with example usage: test_channel(inceptionv1) without return types