anchor.diff:  
   library resumable.base;
   
  +import 'dart:async';
   import 'dart:html';
   
   typedef String IdGenerator();
  
positive.code:   ResumableChunk(this._resumable, this._resumableFile, this._offset, this._callback);
  
  
  }
negative.code: 
    // Events
  
    StreamController<FileSuccessEvent> _fileSuccessController = new StreamController<FileSuccessEvent>();
    Stream<FileSuccessEvent> get onFileSuccess => _fileSuccessController.stream;
  
    StreamController<FileProgressEvent> _fileProgressController = new StreamController<FileProgressEvent>();
    Stream<FileProgressEvent> get onFileProgress => _fileProgressController.stream;
  
  }
  
  class ResumableFile {
  