func Gzip() *compression {
	reader := func(buffer io.Reader) (io.ReadCloser, error) {
		return gzip.NewReader(buffer)
	}
	writer := func(buffer io.Writer) (io.WriteCloser, error) {
		return gzip.NewWriter(buffer), nil
	}
	return &compression{writer: writer, reader: reader, ContentEncoding: "gzip"}
}