code: def test_optflow():
      if not is_of_supported():
          raise SkipTest(
              "Optical Flow is not supported on this platform"
          )
      for output_grid in [1, 2, 4]:
          hint_grid = random.choice([None, 1, 2, 4, 8])
          for use_temporal_hints in [True, False]:
              yield check_optflow, output_grid, hint_grid, use_temporal_hints
  
imports: import os
  import numpy
  import platform
  import random
  import cv2
  from nvidia.dali.pipeline import pipeline_def
  from nvidia.dali import fn, types
  from test_utils import get_dali_extra_path, get_arch
  from nose_utils import raises, assert_raises
  from nose import SkipTest
label_desc: Use image node_id 9 for calling a global function with example usage: test_optflow() without return types