public static boolean isValidAddress(String input) {
        return isValidAddress(input, ADDRESS_LENGTH_IN_HEX);
    }
@Test
    public void testIsValidAddress() {
        assertTrue(isValidAddress(SampleKeys.ADDRESS));
        assertTrue(isValidAddress(SampleKeys.ADDRESS_NO_PREFIX));

        assertFalse(isValidAddress(""));
        assertFalse(isValidAddress(SampleKeys.ADDRESS + 'a'));
        assertFalse(isValidAddress(SampleKeys.ADDRESS.substring(1)));
    }