code: def test_matrix_from_3d_array():
      """Test the topology using the nipy.graph approach"""
      toto = np.ones(shape[:3])
      sm = smatrix_from_3d_array(toto, 6)
      ne = 3 * np.prod(shape[:3])
      for d in range(3):
          ne -= np.prod(shape[:3]) / shape[d]
      ne *= 2
      print(sm.data, ne)
      assert (sm.data > 0).sum() == ne
  
imports: import nibabel.gifti
  import numpy
  from nibabel import Nifti1Image
  from numpy.testing import assert_almost_equal, assert_array_equal
  from ..discrete_domain import domain_from_binary_array, domain_from_image, domain_from_mesh, grid_domain_from_binary_array, grid_domain_from_image, grid_domain_from_shape, smatrix_from_3d_array, smatrix_from_nd_array, smatrix_from_nd_idx
label_desc: Use image node_id 8 for calling a global function with example usage: test_matrix_from_3d_array() without return types