code: def strain_out_of_plane(self, **kwargs):
          '''
          Returns the out-of-plane strain assuming no lattice relaxation, which
          is negative for tensile strain and positive for compressive strain.
          This is the strain measured by X-ray diffraction (XRD) symmetric
          omega-2theta scans.
          '''
          if self._strain_out_of_plane is not None:
              return self._strain_out_of_plane
          else:
              return (-2 * self.unstrained.c12(**kwargs) /
                      self.unstrained.c11(**kwargs) *
                      self.strain_in_plane(**kwargs)      f strain_out_of_plane(self, **kwargs):
          '''
          Returns the out-of-plane strain assuming no lattice relaxation, which
          is negative for tensile strain and positive for compressive strain.
          This is the strain measured by X-ray diffraction (XRD) symmetric
          omega-2theta scans.
          '''
          if self._strain_out_of_plane is not None:
              return self._strain_out_of_plane
          else:
              return (-2 * self.unstrained.c12(**kwargs) /
                      self.unstrained.c11(**kwargs) *
                      self.strain_in_plane(**kwargs)      )
docs: Returns the out-of-plane strain assuming no lattice relaxation, which
          is negative for tensile strain and positive for compressive strain.
          This is the strain measured by X-ray diffraction (XRD) symmetric
          omega-2theta scans.