@Test
public void testLazyFlatMapEmptyOutput() {

  // test empty output
  List<Integer> eval = mlazy(asList(1, 2, 3))
          .flatMap(new Function<Integer, Iterator<Integer>>() {
            @Override
            public Iterator<Integer> apply(Integer integer) {
              return Option.<Integer>none().iterator();
            }
          })
          .eval();
  assertTrue(eval.isEmpty());
}