if (!isDigits(s)) {
            return null;
        }

        try {
            long longValue = Long.parseLong(s);
            if (longValue > Integer.MAX_VALUE) {
                return null;
            }
            return (int) longValue;
        } catch (NumberFormatException e) {
            // should never happen since checked isDigits(s) before
            return null;

        }
    }

    private static Item parseItem(boolean isDigit, String buf) {
        return parseItem(false, isDigit, buf);
    }

    private static Item parseItem(boolean isCombination, boolean isDigit, String buf) {
        if (isCombination) {
            return new CombinationItem(buf.replace("-", ""));
        } else if (isDigit) {
            buf = stripLeadingZeroes(buf);

		return nil
	}

	// normalize the name to letters, digits, _ or $
	valid := true
	cleaned := strings.Map(func(r rune) rune {
		switch {
		case unicode.IsLetter(r):
			return 'a'
		case unicode.IsDigit(r):
			return '0'
		case r == '_', r == '$':
			return r
		default:
			valid = false
			return -1
		}
	}, name)

	if valid {
		// check for simple name or quoted name

   */
  @Deprecated
  public static CharMatcher digit() {
    return Digit.INSTANCE;
  }

  /**
   * Determines whether a character is a BMP digit according to {@linkplain Character#isDigit(char)
   * Java's definition}. If you only care to match ASCII digits, you can use {@code inRange('0',
   * '9')}.
   *
   * @deprecated Many digits are supplementary characters; see the class documentation.