// (1, 2, 3, 4, 5, 6) Seq.of(1, 2, 3).concat(Seq.of(4, 5, 6)); // true Seq.of(1, 2, 3, 4).contains(2); // true Seq.of(1, 2, 3, 4).containsAll(2, 3); // true Seq.of(1, 2, 3, 4).containsAny(2, 5); // (tuple(1, "A"), tuple(1, "B"), tuple(2, "A"), tuple(2, "B")) Seq.of(1, 2).crossJoin(Seq.of("A", "B")); // (tuple(1, 1), tuple(1, 2), tuple(2, 1), tuple(2, 2)) Seq.of(1, 2).crossSelfJoin() // (1, 2, 3, 1

