def test_riffle(self):
        self.assertEqual(list(riffle(range(5), "/")),
                         [0, "/", 1, "/", 2, "/", 3, "/", 4])

        self.assertEqual(list(riffle([], "/")), [])
def wl_print(*payload):
    return wl_side_effect(wl.Print(wl.Row(riffle(payload, " "))))