code: func (e GobEncoder) Serialize(src interface{}) ([]byte, error) {
  	buf := new(bytes.Buffer)
  	enc := gob.NewEncoder(buf)
  	if err := enc.Encode(src); err != nil {
  		return nil, cookieError{cause: err, typ: usageError}
  	}
  	return buf.Bytes(), nil
  }
docs: // Serialization --------------------------------------------------------------
  // Serialize encodes a value using gob.