code: func HexToBytes(s HexString) ([]byte, error) {
  	s2 := string(s)
  	if strings.HasPrefix(s2, "0x") || strings.HasPrefix(s2, "0X") {
  		s2 = s2[2:]
  	}
  	return hex.DecodeString(s2)
  }
docs: // HexToBytes reutrns the bytes represented by the hex of string s.