我正在学习Rx，我想知道我如何才能打印出重试到控制台，例如“重试#1”，“重试#2”等。我看到一些人使用.Dump扩展方法，我找不到。

using System.Reactive.Concurrency;
using System.Reactive.Linq;
using System.Reactive.Threading.Tasks;

var test = new Test(new HttpClient());
var result = await test.GetAsync();
Console.WriteLine($"Result: {result}");

public sealed class Test
{
    private readonly HttpClient _httpClient;

    public Test(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public Task<string> GetAsync()
    {
        return Observable
            .FromAsync(() => _httpClient.GetAsync("http://www.mocky.io/v2/5e307edf3200005d00858b49"))
            .SubscribeOn(TaskPoolScheduler.Default)
            .Retry(5)
            .Timeout(TimeSpan.FromSeconds(5))
            .Do(x => Console.WriteLine($"Is message successful? {x.IsSuccessStatusCode}"))
            .SelectMany(async x =>
            {
                var response = await x.Content.ReadAsStringAsync();
                return response;
            })
            .Catch<string, TimeoutException>(_ => Observable.Return("Timeout"))
            .Catch<string, Exception>(ex => Observable.Return(ex.Message))
            .ToTask();
    }
}