xlHeaderVersion = 2
	xlMetaVersion   = 3
)

func decodeXLHeaders(buf []byte) (versions int, b []byte, e error) {
	hdrVer, buf, e := msgp.ReadUintBytes(buf)
	if e != nil {
		return 0, buf, e
	}
	metaVer, buf, e := msgp.ReadUintBytes(buf)
	if e != nil {
		return 0, buf, e
	}
	if hdrVer > xlHeaderVersion {
		return 0, buf, fmt.Errorf("decodeXLHeaders: Unknown xl header version %d", metaVer)
	}