@Test
 public void tap() {
   MutableList<Integer> tapResult = Lists.mutable.of();
   Interval interval = Interval.fromTo(10, -10).by(-5);
   LazyIterable<Integer> lazyTapIterable = interval.tap(tapResult::add);
   lazyTapIterable.each(x -> {}); // force evaluation
   Assert.assertEquals(interval, tapResult);
 }