clone(node) {
   // e.g. document fragment
   if (node.type === 'root') {
     var serialized = serializer.serialize(node);
     var newParser = new parse5.Parser(parse5.TreeAdapters.htmlparser2);
     return newParser.parseFragment(serialized);
   } else {
     var temp = treeAdapter.createElement("template", null, []);
     treeAdapter.appendChild(temp, node);
     var serialized = serializer.serialize(temp);
     var newParser = new parse5.Parser(parse5.TreeAdapters.htmlparser2);
     return newParser.parseFragment(serialized).childNodes[0];
   }
 }

export function serializeDocument(document: Object, pretty?: boolean): string {
  const doc = serializer.serialize(document);
  if (pretty) {
    const beautify: any = require('js-beautify');
    return beautify.html(doc, {indent_size: 2});
  }
  return doc;
}

 getOuterHTML(el) {
   serializer.html = '';
   serializer._serializeElement(el);
   return serializer.html;
 }

 getInnerHTML(el) { return serializer.serialize(this.templateAwareRoot(el)); }

export function serializeDocument(document: Object): string {
  return serializer.serialize(document);
}