private function addOptionalQueryParameters($apiKey, $language, $region)
    {
        if ($apiKey) {
            $this->endpoint = $this->buildQuery('key', $apiKey);
        }

        if ($language) {
            $this->endpoint = $this->buildQuery('language', $language);
        }

        if ($region) {
            $this->endpoint = $this->buildQuery('region', $region);
        }
    }