public function __construct($base_url = '')
{
$this->base_url = !empty($base_url) ? rtrim($base_url, "/") : '';
$this->curl = curl_init();
curl_setopt($this->curl, CURLOPT_USERAGENT, "RestAgent/1.0");
curl_setopt($this->curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($this->curl, CURLOPT_HEADER, 1);
curl_setopt($this->curl, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($this->curl, CURLOPT_TIMEOUT_MS, self::DEFAULT_TIMEOUT);
curl_setopt($this->curl, CURLOPT_FORBID_REUSE, false);
// Connection-pool for CURL
}