def test__merge4():
seed(time())
xs = [sample(range(100), randint(0, 100)) for _ in range(randint(0, 100))]
ys = (sorted(x) for x in xs)
assert list(merge(*ys)) == sorted(chain(*xs))
def test__merge3():
seed(time())
xs = [sample(range(100), 5) for _ in range(4)]
xs.append([])
ys = (sorted(x) for x in xs)
assert list(merge(*ys)) == sorted(chain(*xs))