code: def test_mix_color_bw():
      numpy.random.seed(32)
      for color in range(3):
          images = [
              numpy.random.uniform(
                  size=(20, 10, 3) if i == color else (20, 10)
              ).astype(numpy.float32)
              for i in range(3)
          ]
          workspace, module = make_place_workspace(images)
          module.run(workspace)
          image = workspace.image_set.get_image(OUTPUT_IMAGE_NAME)
          pixel_data = image.pixel_data
  
          for j, p in enumerate(images):
              jj = 10 * j
              if j == color:
                  assert numpy.all(
                      pixel_data[:, jj : (jj + 10), :] == p
                  )
              else:
                  for k in range(3):
                      assert numpy.all(
                          pixel_data[:, jj : (jj + 10), k] == p
                      )
  
imports: import numpy
  import six.moves
  import cellprofiler_core.image
  import cellprofiler_core.measurement
  import cellprofiler.modules.tile
  import cellprofiler_core.object
  import cellprofiler_core.pipeline
  import cellprofiler_core.workspace
  import tests.frontend.modules
label_desc: Use image node_id 17 for calling a global function with example usage: test_mix_color_bw() without return types