code: def test_3d_inactive():
      n = 30
      lx, ly, lz = n, n, n
      data, labels = make_3d_syntheticdata(lx, ly, lz)
      labels[5:25, 26:29, 26:29] = -1
      with expected_warnings(
          ['"cg" mode|CObject type|scipy.sparse.linalg.cg']
      ):
          labels = random_walker(data, labels, mode="cg")
      assert (
          labels.reshape(data.shape)[13:17, 13:17, 13:17] == 2
      ).all()
      assert data.shape == labels.shape
  
imports: import numpy
  from skimage._shared import testing
  from skimage._shared._warnings import expected_warnings
  from skimage._shared.testing import xfail, arch32
  from skimage.segmentation import random_walker
  from skimage.transform import resize
label_desc: Use image node_id 12 for calling a global function with example usage: test_3d_inactive() without return types