compress.go
func AppendGunzipBytes(dst, src []byte) ([]byte, error) {
	w := &byteSliceWriter{dst}
	_, err := WriteGunzip(w, src)
	return w.b, err
}
func AppendGunzipBytes(dst, src []byte) ([]byte, error) {
	w := &byteSliceWriter{dst}
	_, err := WriteGunzip(w, src)
	return w.b, err
}
// AppendGunzipBytes appends gunzipped src to dst and returns the resulting dst.