private function make($verb, $fetchDetails = null)
    {
        if (isset($this->cache[$verb])) {
            return $this->cache[$verb];
        }

        $data = $this->service->fetch(
            $this->word,
            $verb,
            is_null($fetchDetails) ? $this->prefetchDetails : (bool) $fetchDetails
        );

        if ($data === false) {
            return false;
        }
        $this->cache = array_merge($this->cache, $data);

        return $this->cache[$verb];
    }