anchor.diff:    int _state = _START;
     int _boundaryIndex = 2;
   
  -  // Current index in the data buffer. If index is negative then it
  -  // is the index into the artificial prefix of the boundary string.
  +  /// Current index into [_buffer].
  +  ///
  +  /// If index is negative then it is the index into the artificial prefix of
  +  /// the boundary string.
     int _index;
     List<int> _buffer;
   
     BoundMultipartStream(this._boundary, Stream<List<int>> stream) {
  -    _controller = StreamController(
  -        sync: true,
  -        onPause: _pauseStream,
  -        onResume: _resumeStream,
  -        onCancel: () {
  -          _controllerState = _CONTROLLER_STATE_CANCELED;
  -          _tryPropagateControllerState();
  -        },
  -        onListen: () {
  -          _controllerState = _CONTROLLER_STATE_ACTIVE;
  -          _subscription = stream.listen((data) {
  -            assert(_buffer == null);
  -            _subscription.pause();
  -            _buffer = data;
  -            _index = 0;
  -            _parse();
  -          }, onDone: () {
  -            if (_state != _DONE) {
  -              _controller
  -                  .addError(MimeMultipartException('Bad multipart ending'));
  -            }
  -            _controller.close();
  -          }, onError: _controller.addError);
  -        });
  +    _controller
  +      ..onPause = _pauseStream
  +      ..onResume = _resumeStream
  +      ..onCancel = () {
  +        _controllerState = _CONTROLLER_STATE_CANCELED;
  +        _tryPropagateControllerState();
  +      }
  +      ..onListen = () {
  +        _controllerState = _CONTROLLER_STATE_ACTIVE;
  +        _subscription = stream.listen((data) {
  +          assert(_buffer == null);
  +          _subscription.pause();
  +          _buffer = data;
  +          _index = 0;
  +          _parse();
  +        }, onDone: () {
  +          if (_state != _DONE) {
  +            _controller
  +                .addError(MimeMultipartException('Bad multipart ending'));
  +          }
  +          _controller.close();
  +        }, onError: _controller.addError);
  +      };
     }
   
     void _resumeStream() {
  
positive.code: 
    int _controllerState = _CONTROLLER_STATE_IDLE;
  
    StreamController<MimeMultipart> _controller;
  
    Stream<MimeMultipart> get stream => _controller.stream;
  
  
negative.code: import 'char_code.dart';
  import 'mime_shared.dart';
  
  /// Bytes for '()<>@,;:\\"/[]?={} \t'.
  const _SEPARATORS = [
    40,
    41,
  