code: func ParseUint64(s string) (uint64, bool) {
  	if s == "" {
  		return 0, true
  	}
  	if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") {
  		v, err := strconv.ParseUint(s[2:], 16, 64)
  		return v, err == nil
  	}
  	v, err := strconv.ParseUint(s, 10, 64)
  	return v, err == nil
  }
docs: // ParseUint64 parses s as an integer in decimal or hexadecimal syntax.
  // Leading zeros are accepted. The empty string parses as zero.