@Test
public void shouldReturnEmptyIfBothAreEmpty() throws Exception {

  ImmutableList<Integer> a = ImmutableList.of();
  ImmutableList<String> b = ImmutableList.of();
  NestedLoopPairIterable<Integer, String> ible = NestedLoopPairIterable.of(a, b);
  assertEquals(0, size(ible));
}