How to update RevSlider Plugin after updating to PHP7

After updating to PHP7, login to the admin of wordpress, there would be an error as follows:

revslider\inc_php\framework\base_admin.class.php on line 73

The solution is to go to the file and update in the line 22 as follows:

    private static $menuRole = self::ROLE_ADMIN;
//private static $arrMetaBoxes = "";