code: func parseTwoNumeric(input string) (int, string) {
  	if len(input) > 1 && input[0] == '0' {
  		return 0, input[1:]
  	}
  	matched := twoDigitRegex.FindAllString(input, -1)
  	if len(matched) == 0 {
  		return 0, input
  	}
  
  	str := matched[0]
  	v, err := strconv.ParseInt(str, 10, 64)
  	if err != nil {
  		return 0, input
  	}
  	return int(v), input[len(str):]
  }
docs: // parseTwoNumeric is used for pattens 0..31 0..24 0..60 and so on.
  // It returns the parsed int, and remain data after parse.