code: def test_fwdti_jac_multi_voxel():
      fwdm = fwdti.FreeWaterTensorModel(gtab_2s, "WLS")
      fwdm.fit(DWI[0, :, :])
  
      # no f transform
      fwdm = fwdti.FreeWaterTensorModel(
          gtab_2s, "NLS", f_transform=False, jac=True
      )
      fwefit = fwdm.fit(DWI[0, :, :])
      Ffwe = fwefit.f
      assert_array_almost_equal(Ffwe, GTF[0, :])
  
      # with f transform
      fwdm = fwdti.FreeWaterTensorModel(
          gtab_2s, "NLS", f_transform=True, jac=True
      )
      fwefit = fwdm.fit(DWI[0, :, :])
      Ffwe = fwefit.f
      assert_array_almost_equal(Ffwe, GTF[0, :])
  
imports: import numpy
  import dipy.reconst.dti
  import dipy.reconst.fwdti
  from dipy.reconst.fwdti import fwdti_prediction
  from numpy.testing import assert_array_almost_equal, assert_almost_equal, assert_raises
  from dipy.reconst.dti import from_lower_triangular, decompose_tensor, fractional_anisotropy
  from dipy.reconst.fwdti import lower_triangular_to_cholesky, cholesky_to_lower_triangular, nls_fit_tensor, wls_fit_tensor
  from dipy.sims.voxel import multi_tensor, single_tensor, all_tensor_evecs, multi_tensor_dki
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.core.gradients import gradient_table
  from dipy.data import get_fnames
label_desc: Use image node_id 9 for calling a global function with example usage: test_fwdti_jac_multi_voxel() without return types