anchor.diff:  part of domnode;
  +// TODO: remove validator y sanitizer from constructors
  +// TODO: simplify the '$' function
  +// TODO: add a 'query' function
   
   /**
    * This class represents one or more DOM elements.
  
positive.code:     _elements = elements;
    }
  
    DomNode.fromString(String str,
        {String type: 'text/xml',
        NodeValidator validator,
  
negative.code:       throw new ArgumentError(new ParserError(result).toString());
      }
  
      DocumentFragment fragment = document.createDocumentFragment();
      fragment.appendHtml(str, validator: _validator, treeSanitizer: sanitizer);
      _elements = new List<Element>.from(fragment.children);
    }
  
    List<Element> get elements => this._elements;
  