public function storeSubscriber(Subscriber $subscriber, string $topic): void
    {
        $topicKey = self::TOPIC_KEY.".{$topic}";
        $subscriberKey = self::SUBSCRIBER_KEY.".{$subscriber->channel}";

        $topic = $this->cache->has($topicKey)
            ? json_decode($this->cache->get($topicKey), true)
            : [];

        $topic[] = $subscriber->channel;

        $this->cache->forever($topicKey, json_encode($topic));
        $this->cache->forever($subscriberKey, $subscriber);
    }