code: def test_build_gaussian_pyramid_gray():
      rows, cols = image_gray.shape
      pyramid = pyramids.pyramid_gaussian(
          image_gray, downscale=2, channel_axis=None
      )
      for layer, out in enumerate(pyramid):
          layer_shape = (rows / 2**layer, cols / 2**layer)
          assert_array_equal(out.shape, layer_shape)
  
imports: import math
  import pytest
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal, assert_equal
  from skimage import data
  from skimage._shared.utils import _supported_float_type
  from skimage.transform import pyramids
label_desc: Use image node_id 9 for calling a global function with example usage: test_build_gaussian_pyramid_gray() without return types