Sets up all sub-parsers when help is requested.

def format_help(self):
        """Sets up all sub-parsers when help is requested."""
        if self._subparsers:
            for action in self._subparsers._actions:
                if isinstance(action, LazySubParsersAction):
                    for parser_name, parser in action._name_parser_map.iteritems():
                        action._setup_subparser(parser_name, parser)
        return super(LazyArgumentParser, self).format_help()