@Test
public void testLazyEachIndex() {

  final int[] sum = {0};
  mlazy(asList(1, 2, 3, 4, 5))
          .eachIndex(new Effect2<Integer, Integer>() {
            @Override
            public void run(Integer o, Integer i) {
              sum[0] += (o * i);
            }
          })
          .eval();
  assertEquals(40, sum[0]);
}