code: def set_default_unit(self, twig=None, unit=None, **kwargs):
          
          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)
docs: TODO: add documentation