@Test
public void testIteratorThree() {

    CartesianProductIterable<String> set = CartesianProductIterable.of(source.subList(0, 3));
    assertThat(set, contains(
            Pair.of("A", "B"),
            Pair.of("A", "C"),
            Pair.of("B", "C")
    ));
    assertEquals(3, Iterables.size(set));
}