code: def test_no_motion_3d():
      rng = np.random.default_rng(0)
      img = rng.normal(size=(64, 64, 64))
  
      flow = optical_flow_ilk(img, img)
  
      assert np.all(flow == 0)
  
file_path: scikit-image/skimage/registration/tests/test_ilk.py
imports: import numpy
  import pytest
  from skimage._shared.utils import _supported_float_type
  from skimage.registration import optical_flow_ilk
  from .test_tvl1 import _sin_flow_gen
label_desc: Use image node_id 4 for calling a global function with example usage: test_no_motion_3d() without return types