anchor.diff:      }
     });
   
  -  if (env["verbose"]) {
  +  if (msg.verbose) {
       final end = new DateTime.now().millisecondsSinceEpoch;
       print("${msg.workerName}: Finished processing ${files.length} files. "
             "Took ${end - start} ms.");
  
positive.code: 
  class WorkMessage {
    final String workerName;
    final Map environment;
    final List files;
    final SendPort replyPort;
    WorkMessage(this.workerName, this.environment, this.files, this.replyPort);
  }
  
  class ResultMessage {
  
negative.code:   return buckets;
  }
  
  Future<ResultMessage> spawnWorker(name, pkgRoot, sdkRoot, files, verbose) {
    RawReceivePort port = new RawReceivePort();
    var completer = new Completer();
    port.handler = ((ResultMessage msg) {
      completer.complete(msg);
      port.close();
    });
    var msg = new WorkMessage(name, pkgRoot, sdkRoot, files, port.sendPort, verbose);
    Isolate.spawn(worker, msg);
    return completer.future;
  }
  