'Move all existing options into a subgroup named
C{group_name} with description C{msg}.'

def subsume(self, group_name, msg=''):

    opts = [opt for opt in self.options_iter() if (opt.get_opt_string() not in ('--version', '--help'))]
    self.option_groups = []
    subgroup = self.add_option_group(group_name, msg)
    for opt in opts:
        self.remove_option(opt.get_opt_string())
        subgroup.add_option(opt)
