code: def test_both_algs_same_result_donut():
      # Performing this test on data that does not have ambiguities
      n = 48
      a, b = 2.5 / n, -1.25
  
      vol = np.empty((n, n, n), "float32")
      for iz in range(vol.shape[0]):
          for iy in range(vol.shape[1]):
              for ix in range(vol.shape[2]):
                  # Double-torii formula by Thomas Lewiner
                  z, y, x = (
                      float(iz) * a + b,
                      float(iy) * a + b,
                      float(ix) * a + b,
                  )
                  vol[iz, iy, ix] = (
                      (
                          (8 * x) ** 2
                          + (8 * y - 2) ** 2
                          + (8 * z) ** 2
                          + 16
                          - 1.85 * 1.85
                      )
                      * (
                          (8 * x) ** 2
                          + (8 * y - 2) ** 2
                          + (8 * z) ** 2
                          + 16
                          - 1.85 * 1.85
                      )
                      - 64 * ((8 * x) ** 2 + (8 * y - 2) ** 2)
                  ) * (
                      (
                          (8 * x) ** 2
                          + ((8 * y - 2) + 4) * ((8 * y - 2) + 4)
                          + (8 * z) ** 2
                          + 16
                          - 1.85 * 1.85
                      )
                      * (
                          (8 * x) ** 2
                          + ((8 * y - 2) + 4) * ((8 * y - 2) + 4)
                          + (8 * z) ** 2
                          + 16
                          - 1.85 * 1.85
                      )
                      - 64
                      * (
                          ((8 * y - 2) + 4) * ((8 * y - 2) + 4)
                          + (8 * z) ** 2
                      )
                  ) + 1025
  
      vertices1, faces1 = marching_cubes(vol, 0, method="lorensen")[:2]
      vertices2, faces2 = marching_cubes(vol, 0)[:2]
  
      # Old and new alg are different
      assert not _same_mesh(vertices1, faces1, vertices2, faces2)
  
file_path: scikit-image/skimage/measure/tests/test_marching_cubes.py
imports: import numpy
  import pytest
  from numpy.testing import assert_allclose
  from skimage.draw import ellipsoid, ellipsoid_stats
  from skimage.measure import marching_cubes, mesh_surface_area
label_desc: Use image node_id 6 for calling a global function with example usage: test_both_algs_same_result_donut() without return types