@Test
public void testStreamOpt() {

    final Optional<String> sentinel = Optional.of("sentinel");
    Stream<String> strings = Fun.streamOpt(sentinel);
    final Optional<String> testHead = strings.findFirst();
    assertTrue("value should be present: " + testHead, testHead.isPresent());
    assertSame("value should be same as sentinel", sentinel.get(), testHead.get());
}