code: function S3StreamDownload (s3, s3Params, options) {
      var downloader = new Downloader(s3, s3Params, options);
      return new DownloadStream(downloader);
  }
docs: Creates a stream for download via multipart stream to S3.
  
  @params {S3} s3
  @params {Object} s3Params
  @params {Object} options