def test_lazy_sequences_are_lazy():
n = natural_numbers()
assert take(5, n) == [0, 1, 2, 3, 4]
assert not n.realised
def test_hash_codes_of_lazysequences_make_sense():
assert hash(LazySequence([0, 1, 2])) == hash(LazySequence(take(3, natural_numbers())))
assert hash(LazySequence([0, 1, 2, 3])) != hash(LazySequence(take(3, natural_numbers())))