anchor.diff:        writeLine();
       });
   
  -    Future.forEach(_files.collection, (file) {
  +    Future.forEach(_files, (file) {
         writeAscii('--$boundary\r\n');
         writeAscii(_headerForFile(file));
         return writeStreamToSink(file.finalize(), controller)
  
positive.code: 
    static final Random _random = new Random();
  
    /// The total length of the request body, in bytes. This is calculated from
    /// [fields] and [files] and cannot be set manually.
    int get contentLength {
  
negative.code:           encodeUtf8(value).length + "\r\n".length;
      });
  
      for (var file in _files) {
        length += "--".length + _BOUNDARY_LENGTH + "\r\n".length +
            _headerForFile(file).length +
            file.length + "\r\n".length;
  