public function removeNonSatNSNodes()
    {
        $nss = [];
        foreach ($this->xpathQuery('//namespace::*') as $node) {
            $namespace = $node->nodeValue;
            if ($this->isNameSpaceAllowed($namespace)) {
                continue;
            }
            $nss[] = $namespace;
        }
        if (! count($nss)) {
            return;
        }
        foreach ($nss as $namespace) {
            $this->removeNonSatNSNode($namespace);
        }
    }