Return a newly added style object of *style_type* and identified
        by *name*. A builtin style can be defined by passing True for the
        optional *builtin* argument.

def add_style(self, name, style_type, builtin=False):
        """
        Return a newly added style object of *style_type* and identified
        by *name*. A builtin style can be defined by passing True for the
        optional *builtin* argument.
        """
        style_name = BabelFish.ui2internal(name)
        if style_name in self:
            raise ValueError("document already contains style '%s'" % name)
        style = self._element.add_style_of_type(
            style_name, style_type, builtin
        )
        return StyleFactory(style)