public async Task Todo6()
        {
            var tasks = new List <Task>();

            for (var i = 0; i < 200; i++)
            {
                tasks.Add(new Task(async() => await AliceClient.GetAccountAsync()));
            }

            tasks.AsParallel().ForAll(x => x.Start());
            await Task.WhenAll(tasks);

            await AliceClient.CountAsync();

            await AliceClient.CountAsync();

            await AliceClient.CountAsync();

            await AliceClient.CountAsync();

            await AliceClient.CountAsync();

            var account = await(await AliceClient.GetAccountByIdAsync(1)).Response <Account>();

            if (account.Counter != 5)
            {
                throw new Exception($"counter is {account.Counter}");
            }
        }