code: def empty_image(request):
      """
      Empty image fixtures of shape NHWC.
      """
      channels = request.param
      data_shape = (4, 8, 12, channels)
      return np.zeros(data_shape).astype(ART_NUMPY_DTYPE)
  
file_path: adversarial-robustness-toolbox/tests/defences/preprocessor/cutmix/test_cutmix.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import logging
  import numpy
  import pytest
  from numpy.testing import assert_array_equal, assert_array_almost_equal
  from art.config import ART_NUMPY_DTYPE
  from art.defences.preprocessor import CutMix
  from tests.utils import ARTTestException
label_desc: Use image node_id 2 for calling a global function with example usage: empty_image(request) and returns: np