code: def add_to_parser(self, parser):
          
          setts = self.settings
  
          def sorter(x):
              return (setts[x].section, setts[x].order)
  
          for k in sorted(setts, key=sorter):
              setts[k].add_argument(parser)
          return parser
docs: Add this container :attr:`settings` to an existing ``parser``.