bolthelper.go
func (b Bucket) PutGob(k [][]byte, v interface{}) error {
	var bs bytesp.Slice
	if err := gob.NewEncoder(&bs).Encode(&v); err != nil {
		return errorsp.WithStacksAndMessage(err, "encoding %+v failed", v)
	}
	return b.Put(k, bs)
}
func (b Bucket) PutGob(k [][]byte, v interface{}) error {
	var bs bytesp.Slice
	if err := gob.NewEncoder(&bs).Encode(&v); err != nil {
		return errorsp.WithStacksAndMessage(err, "encoding %+v failed", v)
	}
	return b.Put(k, bs)
}
// PutGob serialize v using gob and put it into the key.