code: protected function head($path, array $parameters = array(), $requestHeaders = array())
      {
          if (array_key_exists('ref', $parameters) && is_null($parameters['ref'])) {
              unset($parameters['ref']);
          }
  
          $response = $this->client->getHttpClient()->request($path, null, 'HEAD', $requestHeaders, array(
              'query' => $parameters
          ));
  
          return $response;
      }
docs: Send a HEAD request with query parameters.
  
  @param string $path           Request path.
  @param array  $parameters     HEAD parameters.
  @param array  $requestHeaders Request headers.
  
  @return \Guzzle\Http\Message\Response