public static function handle(LogoutEvent $event)
    {

        // If there is no user, do nothing.
        if (! $event->user)
            return;

        $event->user->login_history()->save(new UserLoginHistory([
            'source'     => Request::getClientIp(),
            'user_agent' => Request::header('User-Agent'),
            'action'     => 'logout',
        ]));

        $message = 'User logged out from ' . Request::getClientIp();
        event('security.log', [$message, 'authentication']);
    }