@GwtIncompatible // Charset not supported by GWT
  public static final Charset US_ASCII = StandardCharsets.US_ASCII;

  /**
   * ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
   *
   * <p><b>Note:</b> this constant is now unnecessary and should be treated as deprecated; use
   * {@link StandardCharsets#ISO_8859_1} instead.
   *
   */
  public static final Charset ISO_8859_1 = StandardCharsets.ISO_8859_1;

  /**

        if (userFriendly.matches("(?i)(?:American|English|ASCII)")) {
          // 1-byte UTF-8 sequences - "American" ASCII text
          return 0x80;
        } else if (userFriendly.matches("(?i)(?:French|Latin|Western.*European)")) {
          // Mostly 1-byte UTF-8 sequences, mixed with occasional 2-byte
          // sequences - "Western European" text
          return 0x90;

        if (userFriendly.matches("(?i)(?:American|English|ASCII)")) {
          // 1-byte UTF-8 sequences - "American" ASCII text
          return 0x80;
        } else if (userFriendly.matches("(?i)(?:French|Latin|Western.*European)")) {
          // Mostly 1-byte UTF-8 sequences, mixed with occasional 2-byte
          // sequences - "Western European" text
          return 0x90;

func BenchmarkIndexRuneASCII(b *testing.B) {
	benchBytes(b, indexSizes, bmIndexRuneASCII(IndexRune))
}

func BenchmarkIndexRuneUnicode(b *testing.B) {
	b.Run("Latin", func(b *testing.B) {
		// Latin is mostly 1, 2, 3 byte runes.
		benchBytes(b, indexSizes, bmIndexRuneUnicode(unicode.Latin, 'é'))
	})
	b.Run("Cyrillic", func(b *testing.B) {
		// Cyrillic is mostly 2 and 3 byte runes.

    return JavaDigit.INSTANCE;
  }

  /**
   * Determines whether a character is a BMP letter according to {@linkplain
   * Character#isLetter(char) Java's definition}. If you only care to match letters of the Latin
   * alphabet, you can use {@code inRange('a', 'z').or(inRange('A', 'Z'))}.
   *
   * @deprecated Most letters are supplementary characters; see the class documentation.