def set_default_unit(self, twig=None, unit=None, **kwargs):
        """
        TODO: add documentation
        """
        if twig is not None and unit is None:
            # then try to support value as the first argument if no matches with twigs
            if isinstance(unit, u.Unit) or not isinstance(twig, str):
                unit = twig
                twig = None

            elif not len(self.filter(twig=twig, check_default=check_default, **kwargs)):
                unit = twig
                twig = None

        return self.get_parameter(twig=twig, **kwargs).set_default_unit(unit)