code: public function getAvailableOptions($domain)
      {
          $domain = (string)$domain;
          if (!$domain)
              throw new BadMethodCallException('Parameter $domain is missing.');
          try {
              $r = $this->get('vps/' . $domain . '/availableOptions')->send();
          } catch (ClientErrorResponseException $e) {
              if ($e->getResponse()->getStatusCode() == '404' && json_decode($e->getResponse()->getBody())->message == "No options found")
                  return "[]";
              else
                  throw new VpsException($e->getMessage(), $e->getCode(), $e);
          } catch (\Exception $e) {
              throw new VpsException($e->getMessage(), $e->getCode(), $e);
          }
          return $r->getBody(true);
      }
docs: Get available Options
  
  @param string $domain
  @return mixed
  @throws Exception\VpsException
  @throws BadMethodCallException
  @throws Exception\VpsNotFoundException