anchor.diff:  
     return {
       'port': receivePort.sendPort,
  -    'primaryInput': _serializeAsset(transform.primaryInput)
  +    'primaryInput': serializeAsset(transform.primaryInput)
     };
  -}
  -
  -/// Converts a serializable map into an [Asset].
  -Asset _deserializeAsset(Map asset) {
  -  return new Asset.fromStream(
  -      _deserializeId(asset['id']),
  -      _deserializeStream(asset['stream']));
  -}
  -
  -/// A transformer that deserializes the values in a stream sent by
  -/// [_serializeStream].
  -StreamSubscription _deserializeTransformer(Stream input, bool cancelOnError) {
  -  var subscription;
  -  var transformed = input.transform(new StreamTransformer.fromHandlers(
  -      handleData: (data, sink) {
  -    if (data['type'] == 'data') {
  -      sink.add(data['data']);
  -    } else if (data['type'] == 'error') {
  -      sink.addError(CrossIsolateException.deserialize(data['error']));
  -    } else {
  -      assert(data['type'] == 'done');
  -      sink.close();
  -      subscription.cancel();
  -    }
  -  }));
  -  subscription = transformed.listen(null, cancelOnError: cancelOnError);
  -  return subscription;
  -}
  -
  -/// Convert a [SendPort] whose opposite is waiting to send us a stream into a
  -/// [Stream].
  -///
  -/// No stream data will actually be sent across the isolate boundary until
  -/// someone subscribes to the returned stream.
  -Stream _deserializeStream(SendPort sendPort) {
  -  return callbackStream(() {
  -    var receivePort = new ReceivePort();
  -    sendPort.send(receivePort.sendPort);
  -    return receivePort.transform(
  -        const StreamTransformer(_deserializeTransformer));
  -  });
   }
   
   /// Converts a serializable map into an [AssetId].
  
positive.code: import 'dart:mirrors';
  
  import 'http://<<HOST_AND_PORT>>/packages/source_maps/span.dart';
  import 'http://<<HOST_AND_PORT>>/packages/stack_trace/stack_trace.dart';
  import 'http://<<HOST_AND_PORT>>/packages/barback/barback.dart';
  
  /// Sets up the initial communication with the host isolate.
  void main(_, SendPort replyTo) {
  
negative.code:   /// Creates a transform from a serializable map sent from the host isolate.
    ForeignTransform(Map transform)
        : _port = transform['port'],
          primaryInput = deserializeAsset(transform['primaryInput']) {
      _logger = new TransformLogger((assetId, level, message, span) {
        _call(_port, {
          'type': 'log',
  