code: func (u Uint64Slice) Value() (driver.Value, error) {
  	var ss []string
  	for i := 0; i < len(u); i++ {
  		tmp := strconv.FormatUint(u[i], 10)
  		ss = append(ss, tmp)
  	}
  	return "{" + strings.Join(ss, ",") + "}", nil
  }
docs: // Value converts to a slice of uint64.