public function purgeNonce()
    {
        $nonce_list = $this->getVariable('nonce_list', array());
        $new_nonce_list = array();
        if (count($nonce_list) > 0) {
            $stop_nonce = time() - 1800;
            foreach ($nonce_list as $key => $word) {
                if (count($word) > 0) {
                    $this->purgeNonceWord($key, $word, $stop_nonce, $new_nonce_list);
                }
            }
        }

        if (count($new_nonce_list) > 0) {
            $this->setVariable('nonce_list', $new_nonce_list);
        } else {
            $this->unsetVariable('nonce_list');
        }
    }