public function _request($url, $method, $body, $content_type = null)
{
$rest = new RESTClient($this->key, $this->secret, $content_type);
$rest->createRequest($url, $method, $body);
$rest->sendRequest();
$response = $rest->getResponse();
if ($response[0] == 401) {
throw new Unauthorized();
}
return $response;
}
