anchor.diff:  class Replies {
     final bool modal;
     final List<String> available;
  +  String _used;
   
     Replies(this.available, {this.modal: false});
  -
  -  const Replies.none()
  -      : modal = false,
  -        available = const [];
   
     Replies.fromJson(Map json)
         : modal = json['modal'],
  -        available = json['replies'];
  +        available = json['replies'],
  +        _used = json['_used'];
   
     toString() => "Replies: $available, Modal: $modal";
   
  -  Map toJson() => {'modal': modal, 'replies': available};
  +  Map toJson() => {'modal': modal, 'replies': available, '_used': _used};
   }
   
   class NarrationEvent {
  
positive.code:   toString() => "Reply: $reply, dialog: $dialogEvent";
  }
  
  bool _notNull(String reply) => reply != null;
  
negative.code:       String forDialogTo,
        String forDialogFrom}) {
      var conditions = [];
  
      if (_notNull(reply)) conditions.add((e) => e.reply == reply);
      if (_notNull(forDialog)) conditions
          .add((e) => e.dialogEvent.dialog == forDialog);
  