? ((Collection<?>) iterable).isEmpty()
        : !iterable.iterator().hasNext();
  }

  public static void assertEmpty(Iterable<?> iterable) {
    if (!isEmpty(iterable)) {
      fail("Not true that " + iterable + " is empty");
    }
  }

  public static void assertEmpty(Map<?, ?> map) {
    if (!map.isEmpty()) {
      fail("Not true that " + map + " is empty");
    }
  }

    Set<Integer> mt = emptySet();
    assertEmpty(cartesianProduct(mt, mt));
  }

  public void testCartesianProduct_binary0x1() {
    Set<Integer> mt = emptySet();
    assertEmpty(cartesianProduct(mt, set(1)));
  }

  public void testCartesianProduct_binary1x0() {
    Set<Integer> mt = emptySet();
    assertEmpty(cartesianProduct(set(1), mt));
  }