docs: def line_spacing_rule(self):
          """
          A member of the :ref:`WdLineSpacing` enumeration indicating how the
          value of :attr:`line_spacing` should be interpreted. Assigning any of
          the :ref:`WdLineSpacing` members :attr:`SINGLE`, :attr:`DOUBLE`, or
          :attr:`ONE_POINT_FIVE` will cause the value of :attr:`line_spacing`
          to be updated to produce the corresponding line spacing.
          """
          pPr = self._element.pPr
          if pPr is None:
              return None
          return self._line_spacing_rule(
              pPr.spacing_line, pPr.spacing_lineRule
          )