protected function getEventSubtype(EventInterface $event)
    {
        $subevent = '';
        if ($event instanceof CtcpEvent) {
            $subevent = 'ctcp.' . strtolower($event->getCtcpCommand());
        } elseif ($event instanceof UserEvent) {
            $subevent = strtolower($event->getCommand());
        } elseif ($event instanceof ServerEvent) {
            $subevent = strtolower($event->getCode());
        }
        return $subevent;
    }