code: def additional_tortuosity_tests():
      # Test tortuosity when rd is zero
      # single voxel
      t = dki_micro.tortuosity(1.7e-3, 0.0)
      assert_almost_equal(t, 0.0)
  
      # multi-voxel
      RDEc = RDE.copy()
      Torc = Tor.copy()
      RDEc[1, 1, 1] = 0.0
      Torc[1, 1, 1] = 0.0
      t = dki_micro.tortuosity(ADE, RDEc)
      assert_almost_equal(Torc, t)
  
file_path: dipy/dipy/reconst/tests/test_dki_micro.py
imports: import numpy
  import random
  import dipy.reconst.dki_micro
  from numpy.testing import assert_array_almost_equal, assert_almost_equal, assert_, assert_raises, assert_allclose
  from dipy.sims.voxel import multi_tensor_dki, _check_directions, multi_tensor
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.core.gradients import gradient_table
  from dipy.data import get_fnames
  from dipy.reconst.dti import eig_from_lo_tri
  from dipy.data import default_sphere, get_sphere
label_desc: Use image node_id 9 for calling a global function with example usage: additional_tortuosity_tests() without return types