code: func (h Hex) ToString() string {
  	s := fmt.Sprintf("%x", h.Value)
  	if len(s)%2 != 0 {
  		s = "0" + s
  	}
  
  	// should never error.
  	b, _ := hex.DecodeString(s)
  	return string(b)
  }
docs: // ToString returns the string representation for hexadecimal literal.