public function sendSparqlSelectQuery($url, $query)
    {
        // because you can't just fire multiple requests with the same CURL class instance
        // we have to be creative and re-create the class everytime a request is to be send.
        // FYI: https://github.com/php-curl-class/php-curl-class/issues/326
        $class = get_class($this->httpClient);
        $phpVersionToOld = version_compare(phpversion(), '5.5.11', '<=');
        // only reinstance the class if its not mocked
        if ($phpVersionToOld && false === strpos($class, 'Mockery')) {
            $this->httpClient = new $class();
        }

        $this->httpClient->setHeader('Accept', 'application/sparql-results+json');
        $this->httpClient->setHeader('Content-Type', 'application/x-www-form-urlencoded');

        return $this->httpClient->post($url, array('query' => $query));
    }