code: def example_withchannels():
      print("Example: WithChannels")
      import numpy as np
      import imgaug.augmenters as iaa
  
      # fake RGB images
      images = np.random.randint(
          0, 255, (16, 128, 128, 3), dtype=np.uint8
      )
  
      # add a random value from the range (-30, 30) to the first two channels of
      # input images (e.g. to the R and G channels)
      aug = iaa.WithChannels(
          channels=[0, 1], children=iaa.Add((-30, 30))
      )
  
      images_aug = aug(images=images)
  
file_path: imgaug/checks/check_readme_examples.py
imports: from __future__ import print_function, division
  import functools
label_desc: Use image node_id 16 for calling a global function with example usage: example_withchannels() without return types