using System.CommandLine;

class Program
{
    // <asyncaction>
    static Task<int> Main(string[] args)
    {
        // the "A URL" alias should not contain a whitespace   something like "url"
        Option<string> urlOption = new("--url", "A URL.");
        // ...
    }

    // ...
}

using System.CommandLine;

namespace commandlinetest;

public static class Program
{
  static Task<int> Main(string[] args)
  {
    Option<string> urlOption = new("--url", "url");
    RootCommand rootCommand = new("Handle termination example") { urlOption };

    rootCommand.SetAction((parseResult, cancellationToken) =>
    {
      string? urlOptionValue = parseResult.GetValue(urlOption);
      return DoRootCommand(urlOptionValue, cancellationToken);
    });

    return rootCommand.Parse(args).InvokeAsync();
  }

  public static async Task<int> DoRootCommand(
      string? urlOptionValue, CancellationToken cancellationToken)
  {
    using HttpClient httpClient = new();

    try
    {
      HttpResponseMessage response = await httpClient.GetAsync(urlOptionValue, cancellationToken);
      Console.WriteLine(response);
      return 0;
    }
    catch (OperationCanceledException)
    {
      await Console.Error.WriteLineAsync("The operation was aborted");
      return 1;
    }
  }
}