code: func GetCompressor(namespace string, out io.Writer) (io.WriteCloser, error) {
  	// Higher compression level uses cpu resources more than we want.
  	if isCompressed(namespace) {
  		return zlib.NewWriterLevel(out, zlib.BestSpeed)
  	}
  	return nopCloser{out}, nil
  }
docs: // GetCompressor returns a fresh instance of the compression algorithm.
  //
  // It must be closed after use.
  //
  // It is currently hardcoded to RFC 1950 (zlib).