code: def test_from_lower_triangular():
      result = np.array([[0, 1, 3], [1, 2, 4], [3, 4, 5]])
      D = np.arange(7)
      tensor = from_lower_triangular(D)
      npt.assert_array_equal(tensor, result)
      result = result * np.ones((5, 4, 1, 1))
      D = D * np.ones((5, 4, 1))
      tensor = from_lower_triangular(D)
      npt.assert_array_equal(tensor, result)
  
imports: import warnings
  import numpy
  import numpy.testing
  import scipy.optimize
  import dipy.reconst.dti
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.reconst.dti import ols_resort_msg, axial_diffusivity, color_fa, fractional_anisotropy, from_lower_triangular, geodesic_anisotropy, lower_triangular, mean_diffusivity, radial_diffusivity, TensorModel, trace, linearity, planarity, sphericity, decompose_tensor, _decompose_tensor_nan
  from dipy.io.image import load_nifti_data
  from dipy.data import get_fnames, dsi_voxels, get_sphere
  from dipy.core.subdivide_octahedron import create_unit_sphere
  import dipy.core.gradients
  import dipy.core.sphere
  from dipy.sims.voxel import single_tensor
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 14 for calling a global function with example usage: test_from_lower_triangular() without return types