Xenforo: CAPTCHA for new usergroup

Edit: library/XenForo/Visitor.php

Code:

    /**
     * Returns true if the visitor should be shown a CAPTCHA.
     *
     * @return boolean
     */
    public function showCaptcha()
    {
        return ($this->_user['user_id'] == 0); // TODO: permission
    }

to

Code:

    /**
     * Returns true if the visitor should be shown a CAPTCHA.
     *
     * @return boolean
     */
    public function showCaptcha()
    {
        return ($this->_user['user_id'] == 0 OR $this->isMemberOf(5)); // TODO: permission
    }

This will force members of group id 5 to fill out a captcha. Registered users is usergroup 2.