anchor.diff:  
     Tag(this.key, this.value);
   
  -  String toJson() => '[ "${this.key}", "${this.value}" ]';
  +  toJson() => [this.key, this.value];
   }
   
   /**
  
positive.code:  */
  class SentryStackFrame {
    String _filename, _module, _function;
    int _lineno, _colno;
  
    /**
     * Creates a stackframe object from a line from the stacktrace, e.g.
     *    #0      RavenClientTests._testCaptureException (file:///c:/raven-dart/src/raven_client.dart:28:7)
     */
    SentryStackFrame._fromFrame(String frame) {
      var fileStartIdx = frame.indexOf('file:///');
      if (fileStartIdx >= 0) {
        this._function = parseStackTraceToGetCurrentMethodName(frame);
        this._filename = frame.substring(fileStartIdx+8, frame.lastIndexOf('.dart')+5);
        this._module   = this._filename.split('/').last;
        var lineInfo  = frame.substring(frame.lastIndexOf('.dart')+5, frame.lastIndexOf(')'));
        var linePos   = lineInfo.split(':').where(isNotNullOrEmpty).toList();
        this._lineno   = int.parse(linePos[0]);
        this._colno    = int.parse(linePos[1]);
      }
    }
  
    String _toJson() => '''
  { 
    "filename": "${this._filename}",
    "lineno"  : ${this._lineno},
    "colno"   : ${this._colno},
    "function": "${this._function}",
    "module"  : "${this._module}" 
  }''';
  
    String toJson() => mapOrDefault(this._filename, (_) => _toJson());
  }
  
  /**
  
negative.code:     this.modules    = defaultArg(modules, {}),
      this.exception  = mapOrDefault(exception, (exn) => new SentryException._fromException(exn, stackTrace.toString()));
  
    String toJson() => JSON.encode({
      "event_id"    : this.eventId,
      "message"     : this.message,
      "timestamp"   : this.timestamp.millisecondsSinceEpoch,
      "level"       : this.logLevel.toJson(),
      "logger"      : this.logger,
      "platform"    : this.platform,
      "culprit"     : this.culprit,
      "tags"        : this.tags.map((tag) => tag.toJson()).toList(),
      "extra"       : this.extra,
      "server_name" : this.serverName,
      "modules"     : this.modules,
      "exception"   : [(this.exception == null) ? '' : this.exception.toJson()],
    });
  }