public function getSlot($command, $args): ?int
    {
        $id = \strtoupper($command);

        $slot = null;

        if (isset($this->commands[$id])) {
            $key = $this->commands[$id]($id, $args);

            if (null !== $key) {
                $slot = $this->getSlotByKey($key);
            }
        }

        return $slot;
    }