'Return the style of *style_type* matching *style_id*. Returns the
default for *style_type* if *style_id* is not found or if the style
having *style_id* is not of *style_type*.'

def _get_by_id(self, style_id, style_type):

    style = self._element.get_by_id(style_id)
    if ((style is None) or (style.type != style_type)):
        return self.default(style_type)
    return StyleFactory(style)
