anchor.diff:  }
   
   Response _handler(Request request) {
  -  _stopwatch.start();
  +  final agent = request.headers['user-agent'];
  +  if (agent != null) {
  +    _agents[agent] = (_agents[agent] ?? 0) + 1;
  +  }
   
     if (request.requestedUri.pathSegments.length == 1) {
       switch (request.requestedUri.pathSegments.single) {
  
positive.code: 
          final data = {
            'since boot': _stopwatch.elapsed.toString(),
            'redirects': _redirects,
            'notFounds': _notFound,
            'info': _infoRequests,
            'robot.txt': _robotTxt,
            'Dart version': Platform.version,
            'request headers': SplayTreeMap.of(request.headers),
          };
  
          return Response.ok(
  
negative.code: int _notFound = 0;
  int _robotTxt = 0;
  final _stopwatch = Stopwatch();
  final _agents = <String, int>{};
  
  Handler get handler {
    _stopwatch.start();
  