#nullable enable

​

using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        if (Foo() is List<int>{} bar)

        {

            Console.WriteLine("Foo() beep");

        }

        else

        {

            Console.WriteLine("Foo() boop");

        }

        if (Bar() is List<int>{} qux)

        {

            Console.WriteLine("Bar() beep");

        }

        else

        {

            Console.WriteLine("Bar() boop");

        }

    }

    public static List<int>? Foo()

    {

        return null;

    }

    public static List<int>? Bar()

    {

        return new(){1,2,3};

    }

}