anchor.diff:  class Config {
   
     /**
  -   * If port is -1, secure communications are disabled
  +   * Whether to enable listening to secure communications
  +   */
  +  final bool useSecure;
  +
  +  /**
  +   * Port used for secure communications
      */
     final int sslPort;
   
     /**
  -   * If port is -1, non-secure communications are disabled
  +   * Whether to enable listening to insecure communications
  +   */
  +  final bool useInsecure;
  +
  +  /**
  +   * Port used for insecure communications
      */
     final int port;
   
  -  Config({this.sslPort: 3110, this.port: 3100});
  +  Config({this.useSecure: false,
  +          this.sslPort: 3110,
  +          this.useInsecure: true,
  +          this.port: 3100});
   
   }
   
   class ConfigReader {
   
  -  static const String SSL_PORT = "ssl_port";
  +  static const String SECURE = "secure";
  +  static const String INSECURE = "insecure";
  +
  +  static const String ENABLED = "enabled";
     static const String PORT = "port";
   
     final File _path;
  
positive.code:   ConfigWriter(this._path);
  
    void write(final Config config) {
      var json = {};
      if (_path.existsSync()) {
        json = JSON.decode(_path.readAsStringSync());
        _path.deleteSync();
      }
  
      if (json[ConfigReader.SSL_PORT] == null)
        json[ConfigReader.SSL_PORT] = config.sslPort;
  
      if (json[ConfigReader.PORT] == null)
        json[ConfigReader.PORT] = config.port;
  
      _path.writeAsStringSync(enc.convert(json));
    }
  }
  
negative.code: 
    Config read() {
      var json = JSON.decode(_path.readAsStringSync());
  
      var secure = _fieldCheck(json, SECURE);
      bool useSecure = _fieldCheck(secure, ENABLED);
      int sslPort = _fieldCheck(secure, PORT);
  
      var insecure = _fieldCheck(json, INSECURE);
      bool useInsecure = _fieldCheck(insecure, ENABLED);
      int port = _fieldCheck(json, PORT);
  
      return new Config(useSecure: useSecure,
                        sslPort: sslPort,
                        useInsecure: useInsecure,
                        port: port);
    }
  
    _fieldCheck(Map m, String field) {
  