code: def test_standalone_functions():
      # WLS procedure
      params = wls_fit_tensor(gtab_2s, DWI)
      assert_array_almost_equal(params[..., 12], GTF)
      fa = fractional_anisotropy(params[..., :3])
      assert_array_almost_equal(fa, FAref)
  
      # NLS procedure
      params = nls_fit_tensor(gtab_2s, DWI)
      assert_array_almost_equal(params[..., 12], GTF)
      fa = fractional_anisotropy(params[..., :3])
      assert_array_almost_equal(fa, FAref)
  
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 10 for calling a global function with example usage: test_standalone_functions() without return types