code: function GridFSBucketReadStream(chunks, files, readPreference, filter, options) {
    this.s = {
      bytesRead: 0,
      chunks: chunks,
      cursor: null,
      expected: 0,
      files: files,
      filter: filter,
      init: false,
      expectedEnd: 0,
      file: null,
      options: options,
      readPreference: readPreference
    };
  
    stream.Readable.call(this);
  }
docs: A readable stream that enables you to read buffers from GridFS.
  
  Do not instantiate this class directly. Use `openDownloadStream()` instead.
  
  @class
  @param {Collection} chunks Handle for chunks collection
  @param {Collection} files Handle for files collection
  @param {Object} readPreference The read preference to use
  @param {Object} filter The query to use to find the file document
  @param {Object} [options] Optional settings.
  @param {Number} [options.sort] Optional sort for the file find query
  @param {Number} [options.skip] Optional skip for the file find query
  @param {Number} [options.start] Optional 0-based offset in bytes to start streaming from
  @param {Number} [options.end] Optional 0-based offset in bytes to stop streaming before
  @fires GridFSBucketReadStream#error
  @fires GridFSBucketReadStream#file
  @return {GridFSBucketReadStream} a GridFSBucketReadStream instance.