public static String cleanHexPrefix(String input) {
        if (containsHexPrefix(input)) {
            return input.substring(2);
        } else {
            return input;
        }
    }
@Test
    public void testCleanHexPrefix() {
        assertEquals(Numeric.cleanHexPrefix(""), (""));
        assertEquals(Numeric.cleanHexPrefix("0123456789abcdef"), ("0123456789abcdef"));
        assertEquals(Numeric.cleanHexPrefix("0x"), (""));
        assertEquals(Numeric.cleanHexPrefix("0x0123456789abcdef"), ("0123456789abcdef"));
    }