code: def symmetry_normalised_reflections(self, hkl):
          
          hkl = np.array(hkl, dtype=int, ndmin=2)
          normalised = np.empty(hkl.shape, int)
          R = self.get_rotations().transpose(0, 2, 1)
          for i, g in enumerate(hkl):
              gsym = np.dot(R, g)
              j = np.lexsort(gsym.T)[0]
              normalised[i,:] = gsym[j]
          return normalised
docs: Returns an array of same size as *hkl*, containing the
          corresponding symmetry-equivalent reflections of lowest
          indices.
  
          Example:
  
          >>> from ase.lattice.spacegroup import Spacegroup
          >>> sg = Spacegroup(225)  # fcc
          >>> sg.symmetry_normalised_reflections([[2, 0, 0], [0, 2, 0]])
          array([[ 0,  0, -2],
                 [ 0,  0, -2]])