public static function process($event)
    {
        // Link Lead with User
        if ($event->account_linking->status === 'linked') {
            $authorization_code = $event->account_linking->authorization_code;
            $user_id = str_replace('user_id:', '', $authorization_code);
            
            return self::linkWithExistingUser($event->sender->id, $user_id);
        } // Unlink, Logout user
        
        return self::unlinkWithExistingUser($event->sender->id);
    }