code: func (s *Signature) Encode(w io.Writer) error {
  	if _, err := fmt.Fprintf(w, "%s <%s> ", s.Name, s.Email); err != nil {
  		return err
  	}
  	if err := s.encodeTimeAndTimeZone(w); err != nil {
  		return err
  	}
  	return nil
  }
docs: // Encode encodes a Signature into a writer.