*
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

     *
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

   */
  static BigInteger randomNonNegativeBigInteger(int numBits) {
    int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {
      return new BigInteger(digits, RANDOM_SOURCE).setBit(digits);
    }
  }

  /**
   * Equivalent to calling randomPositiveBigInteger(numBits) and then flipping the sign with 50%

    /**
     * Convert hexadecimal characters to binary integer
     *
     * @param arr the character array containing hex digits
     * @param offset the starting position in the array
     * @param length the number of hex digits to convert
     * @return the integer value of the hex digits
     */
    public static int hex_to_bin(final char[] arr, final int offset, final int length) {
        int value = 0;

    }

    /**
     * Checks if the given character is a valid URL character.
     *
     * Valid URL characters include:
     * - Lowercase letters (a-z)
     * - Uppercase letters (A-Z)
     * - Digits (0-9)
     * - Special characters: . - * _ : / + % = & ? # [ ] @ ~ ! $ ' ( ) , ;
     *
     * @param c the character to check
     * @return {@code true} if the character is a valid URL character, {@code false} otherwise

    private
    fun VersionNumber.format() =
        // reformat according to our versioning scheme, since toString() would typically convert 1.0 to 1.0.0
        // starting with Gradle 9.0, the version number is always 3 digits (SemVer)
        GradleVersion.version("$major.${minor}${if (micro > 0 || major >= 9) ".$micro" else ""}${if (qualifier != null) "-$qualifier" else ""}")

	var (
		c       = d.cur()
		n       float64
		isFloat bool
	)

	// digits first
	switch {
	case c == '0':
		d.scratch.add(c)
		c = d.next()
	case '1' <= c && c <= '9':
		for ; c >= '0' && c <= '9'; c = d.next() {
			n = 10*n + float64(c-'0')
			d.scratch.add(c)
		}
	}

	// . followed by 1 or more digits
	if c == '.' {
		isFloat = true
		d.scratch.add(c)

            """
        ),
    ] = _Unset,
    max_digits: Annotated[
        Union[int, None],
        Doc(
            """
            Maximum number of allow digits for strings.
            """
        ),
    ] = _Unset,
    decimal_places: Annotated[
        Union[int, None],
        Doc(
            """

        assertTrue(CharUtil.isUrlChar('A')); // first uppercase
        assertTrue(CharUtil.isUrlChar('Z')); // last uppercase
        assertTrue(CharUtil.isUrlChar('0')); // first digit
        assertTrue(CharUtil.isUrlChar('9')); // last digit

        // Test characters just outside ranges that are not valid
        assertFalse(CharUtil.isUrlChar('`')); // backtick (just before 'a')

    }

    @Test
    void isAllDigitsHandlesEmptyString() {
        // Empty string technically has no non-digit characters, so it returns true
        assertTrue(UniAddress.isAllDigits(""), "isAllDigits should return true for empty string (no non-digits)");
    }

    /* ---------------------------------------------------------------------