private function buildClient(array $config)
    {
        $client = ClientBuilder::create()
            ->setHosts($config['hosts']);

        if (isset($config['retries'])) {
            $client->setRetries($config['retries']);
        }

        if (isset($config['logging']) and $config['logging']['enabled'] == true) {
            $logger = ClientBuilder::defaultLogger($config['logging']['path'], $config['logging']['level']);
            $client->setLogger($logger);
        }

        return $client->build();
    }