public function create_resumpToken($token, $expirationdatetime, $num_rows, $cursor=null)
    {
        $resump_node = $this->addChild($this->verbNode, "resumptionToken", $token);
        if (isset($expirationdatetime)) {
            $resump_node->setAttribute("expirationDate", $expirationdatetime);
        }
        $resump_node->setAttribute("completeListSize", $num_rows);
        $resump_node->setAttribute("cursor", $cursor);
    }