code: private function firstParamValidation(Event $event)
      {
          $params = $event->getCustomParams();
          return (is_numeric($params[0]) && $params[0] > 0 && $params[0] <= $this->maxDieRolls);
      }
docs: Verify parameter 1 is valid
  
  @param \Phergie\Irc\Plugin\React\Command\CommandEvent $event
  @return boolean