code: def test_blur_effect():
      """Test that the blur metric increases with more blurring."""
      image = astronaut()
      B0 = blur_effect(image, channel_axis=-1)
      B1 = blur_effect(
          gaussian(image, sigma=1, channel_axis=-1), channel_axis=-1
      )
      B2 = blur_effect(
          gaussian(image, sigma=4, channel_axis=-1), channel_axis=-1
      )
      assert 0 <= B0 < 1
      assert B0 < B1 < B2
  
file_path: scikit-image/skimage/measure/tests/test_blur_effect.py
imports: from numpy.testing import assert_array_equal
  from skimage.color import rgb2gray
  from skimage.data import astronaut, cells3d
  from skimage.filters import gaussian
  from skimage.measure import blur_effect
label_desc: Use image node_id 1 for calling a global function with example usage: test_blur_effect() without return types