code: def voigt(self):
          
          v_matrix = np.zeros(self._vscale.shape, dtype=self.dtype)
          this_voigt_map = self.get_voigt_dict(self.rank)
          for ind in this_voigt_map:
              v_matrix[this_voigt_map[ind]] = self[ind]
          if not self.is_voigt_symmetric():
              warnings.warn("Tensor is not symmetric, information may "
                            "be lost in voigt conversion.")
          return v_matrix * self._vscale
docs: Returns the tensor in Voigt notation