public function fileGetContents($file)
    {
        $client = new Client();
        $response = $client->createRequest()
            ->setMethod('get')
            ->setUrl($file)
            ->addHeaders(['user-agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36'])
            ->setOptions([
                'timeout' => $this->readFileTimeout, // set timeout to 1 seconds for the case server is not responding
            ])
            ->send();

        if ($response->isOk) {
            return $response->content;
        }

        throw new \Exception("File get contents '{$file}' error: ".$response->content);
    }