anchor.diff:  
       StringBuffer sb = new StringBuffer();
   
  -    if (attachments.isNotEmpty) {
  -      sb.write(":");
  -      attachments.forEach((Attachment a) => sb.write(" << ${a.fromUrl} >>"));
  -    }
  +//    if (attachments.isNotEmpty) {
  +//      sb.write(":");
  +//      attachments.forEach((Attachment a) => sb.write(" << ${a.fromUrl} >>"));
  +//    }
   
       return '$parsedDateTime:$userId:$text$sb';
     }
  
positive.code:     json['user'] = userId;
      json['text'] = text;
      json['subtype'] = subtype;
  
      json['attachments'] = JSON.encode(attachments);
  
      return json;
    }
  
negative.code:     text = json['text'];
      subtype = json['subtype'];
  
  //    if (json['attachments'] != null && subtype != 'bot_message') {
  //      List<Map> jsonAttachments = json['attachments'];
  //      attachments =
  //          jsonAttachments.map((Map m) => new Attachment.fromJson(m)).toList();
  //    } else {
  //      attachments = [];
  //    }
    }
  
    Map toJson() {
  