code: func (x *Dec) GobEncode() ([]byte, error) {
  	buf, err := x.UnscaledBig().GobEncode()
  	if err != nil {
  		return nil, err
  	}
  	buf = append(append(buf, scaleBytes(x.Scale())...), decGobVersion)
  	return buf, nil
  }
docs: // GobEncode implements the gob.GobEncoder interface.