anchor.diff:        for (TimelineEvent child in children) {
           child.writeTraceToBuffer(buf);
         }
  -      for (var json in traceEvents.where((trace) =>
  -          !collectionEquals(trace.event.json, beginTraceEventJson))) {
  -        buf.writeln(json.toString());
  +      for (var traceEvent in traceEvents.where(
  +          (event) => !collectionEquals(event.json, beginTraceEventJson))) {
  +        buf.writeln(traceEvent.json.toString());
         }
       }
     }
  
positive.code:   TraceEventWrapper(this.event, this.timeReceived)
        : id = _traceEventWrapperId++;
    final TraceEvent event;
    final num timeReceived;
    final int id;
  
    bool processed = false;
  
  
negative.code: 
    String get name => traceEvents.first.event.name;
  
    Map<String, dynamic> get beginTraceEventJson => traceEvents.first.json;
  
    Map<String, dynamic> get endTraceEventJson => traceEvents.last.json;
  
    /// Event duration in micros.
    int get duration => (endTime != null) ? endTime - startTime : null;
  