public async void Unbounded_Take()
        {
            var push = new ReplayAsyncEnumerable <int>();

            var t1 = push.Take(1).AssertResult(1);

            var t2 = push.Take(2).AssertResult(1, 2);

            await push.Next(1);

            await push.Next(2);

            await t1;

            await t2;
        }