docstr: Test a thick vertical line, issue #3861
docstr_tok: ["Test","a","thick","vertical","line",",","issue","#","3861"]
code: def test_vertical_line(self, dtype):
      """Test a thick vertical line, issue #3861"""
      img = np.zeros((9, 9), dtype=dtype)
      img[:, 2] = 1
      img[:, 3] = 2
      img[:, 4] = 3
  
      expected = np.full(img.shape, False)
      expected[:, 3] = True
  
      result = medial_axis(img)
      assert_array_equal(result, expected)
  
imports: import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from scipy.ndimage import correlate
  from skimage import draw
  from skimage._shared.testing import fetch
  from skimage.io import imread
  from skimage.morphology import medial_axis, skeletonize, thin
  from skimage.morphology._skeletonize import G123_LUT, G123P_LUT, _generate_thin_luts
label_desc: Use image node_id 3 for calling the TestMedialAxis obj's underlying member method code with example usage: obj.test_vertical_line(dtype) without return types