code: def normalize_images(images):
      if images is None:
          return None
      if ia.is_np_array(images):
          if images.ndim == 2:
              return images[np.newaxis, ..., np.newaxis]
          if images.ndim == 3:
              return images[..., np.newaxis]
          return images
      if ia.is_iterable(images):
          result = []
          for image in images:
              assert image.ndim in [2, 3], (
                  "Got a list of arrays as argument 'images'. Expected each "
                  "array in that list to have 2 or 3 dimensions, i.e. shape "
                  "(H,W) or (H,W,C). Got %d dimensions "
                  "instead." % (image.ndim,)
              )
  
              if image.ndim == 2:
                  result.append(image[..., np.newaxis])
              else:
                  result.append(image)
          return result
      raise ValueError(
          "Expected argument 'images' to be any of the following: "
          "None or array or iterable of array. Got type: %s."
          % (type(images),)
      )
  
imports: from __future__ import print_function, division, absolute_import
  import functools
  import numpy
  from ..None import imgaug
  from ..None import dtypes
  from .base import IAugmentable
label_desc: Use image node_id 7 for calling a global function with example usage: normalize_images(images) and returns: None, images, result, images, images