code: func (b Bucket) GobValue(k [][]byte, f func(interface{}) error) error {
  	return b.Value(k, func(bs bytesp.Slice) error {
  		var v interface{}
  		if err := gob.NewDecoder(&bs).Decode(&v); err != nil {
  			return errorsp.WithStacksAndMessage(err, "decoding %d bytes buffer failed", len(bs))
  		}
  		return f(v)
  	})
  }
docs: // GobValue retrieves a value written by PutGob and decode it.