Airship\Engine\Hail::downloadFile PHP Method

    public function downloadFile(string $url, string $filename, array $params = []) : ResponseInterface
    {
        $fp = \fopen($filename, 'wb');
        $opts = $this->params($params, $url);
        $opts[\CURLOPT_FOLLOWLOCATION] = true;
        $opts[\CURLOPT_FILE] = $fp;
        $result = $this->client->post($url, $opts);
        \fclose($fp);
        return $result;
    }