code: def test_slic_zero():
      # Same as test_color_2d but with slic_zero=True
      rng = np.random.default_rng(0)
      img = np.zeros((20, 21, 3))
      img[:10, :10, 0] = 1
      img[10:, :10, 1] = 1
      img[10:, 10:, 2] = 1
      img += 0.01 * rng.normal(size=img.shape)
      img[img > 1] = 1
      img[img < 0] = 0
      seg = slic(
          img, n_segments=4, sigma=0, slic_zero=True, start_label=0
      )
  
      # we expect 4 segments
      assert_equal(len(np.unique(seg)), 4)
      assert_equal(seg.shape, img.shape[:-1])
      assert_equal(seg[:10, :10], 0)
      assert_equal(seg[10:, :10], 2)
      assert_equal(seg[:10, 10:], 1)
      assert_equal(seg[10:, 10:], 3)
  
imports: from itertools import product
  import numpy
  import pytest
  from numpy.testing import assert_equal
  from skimage import data, filters, img_as_float
  from skimage._shared.testing import run_in_parallel, expected_warnings
  from skimage.segmentation import slic
label_desc: Use image node_id 13 for calling a global function with example usage: test_slic_zero() without return types