anchor.diff:      
       var enter$ = _input.keyboard$
             .where((e) => e.keyCode == KeyCode.ENTER && e.target.value != '');
  -    
  -
  +   
       lifeCycle$.where((e) => e is WillMountEvent).listen((onData) {
         globalEvent$.listen((m) {
           messages.add(m);
  
positive.code:   final String owner;
    final List<String> receivers;
    final String text;
    
    Message(this.owner, this.receivers, this.text);
    
    toString() => 'from $owner, to $receivers: $text';
  
negative.code:     return 
      div(className: 'panel panel-primary', children: [
        div(className: 'panel-heading', children: receivers.join(', ')),
        span(className:'glyphicon glyphicon-pencil', children: '$_typingString'),
        _body,
        _input
      ]);
  