public function create($key, $value)
    {
        $exists = $this->metaModel::where('key', $key)
            ->exists();

        if ($exists) {
            $message = "Can't create meta (key: $key). ";
            $message .= "Meta already exists";
            throw new \Exception($message);
        }

        $meta = new $this->metaModel;

        $meta->key = $key;
        $meta->value = $value;

        $meta->save();
    }