def style(self, style):
        """
        Set val attribute of <w:rStyle> child element to *style*, adding a
        new element if necessary. If *style* is |None|, remove the <w:rStyle>
        element if present.
        """
        if style is None:
            self._remove_rStyle()
        elif self.rStyle is None:
            self._add_rStyle(val=style)
        else:
            self.rStyle.val = style