func KVFromBytes(bs []byte) (k, v []byte) {
	klen := int(binary.LittleEndian.Uint16(bs[0:2]))
	return bs[2 : 2+klen], bs[2+klen:]
}
func KVFromBytes(bs []byte) (k, v []byte) {
	klen := int(binary.LittleEndian.Uint16(bs[0:2]))
	return bs[2 : 2+klen], bs[2+klen:]
}
// KVFromBytes extracts key-value pair from item bytes returned by iterator