@Test
 public void testParseOptionalHexOk() throws Exception {
   long i = 0x14;
   String s = "0x" + Long.toHexString(i);
   OptionalLong ret = ParseLong.parseOptional(s);
   assertTrue(ret.isPresent());
   assertEquals(i, ret.getAsLong());
 }
 @Test
 public void testParseOptionalNullFail() throws Exception {
   OptionalLong ret = ParseLong.parseOptional(null);
   assertFalse(ret.isPresent());
 }
 @Test
 public void testParseOptionalHexFail() throws Exception {
   String s = "0x12akjhsdr?";
   OptionalLong ret = ParseLong.parseOptional(s);
   assertFalse(ret.isPresent());
 }