/**
     * show next execution datetime for an cron expression.
     *
     * @arguments
     *  expression      string;The cronTab expression. eg: `20 10 * * *`;required
     *
     * @options
     *  -n, --next      int;Show next number exec datetime. default number is 3.
     *  -p, --prev      bool;Show previsions exec datetime
     *
     * @param FlagsParser $fs
     * @param Output $output
     *
     * @throws Exception
     */
    public function someCommand(FlagsParser $fs, Output $output): void
    {
        $expr = $fs->getArg('expression'); // will get string value
        $prev = $fs->getOpt('prev'); // will get bool value
        $nextNum  = $fs->getOpt('next', 3); // will get int value
        $output->colored('Cron Expression: ' . $expr);
    }

    /**
     * Configure for the subcommand `some`
     */
    protected function someConfigure(): void
    {
        // 在独立命令里
        // $fs = $this->getFlags();
        // 在group的子命令里
        $fs = $this->getActionFlags();
        $fs->addArg('topic', 'The language/topic for search. eg: go, php, java, lua, python, js ...');
        $fs->addArg('question', 'The question search.');
        $fs->addOpt('search', 's', 'search by the keywords');
        // $fs->addOpt('T', 't', 'query');
        $fs->setMoreHelp(<<<HELP
<b>Special pages</b>
There are several special pages that are not cheat sheets. Their names start with colon and have special meaning.

.... ...
HELP
        );
        $fs->setExampleHelp([
            '{fullCmd} go reverse list'
        ]);
    }