using System;

class Hoge
{
    private string _helloWorld;
    private char _suffix = '!';

    public string HelloWorld
    {
        get => _helloWorld;
        set => _helloWorld = value ?? throw new ArgumentNullException();
    }

    public string TryGetHelloWorld(out string str)
        => str = (this.HelloWorld is string helloWorld) ? helloWorld : "";

    public ref char GetSuffix() => ref _suffix;
}

class Program
{
    public static void Main()
    {
        (string helloWorld, int, char suffix, double) HelloWorld()
        {
            var hoge = new Hoge() { HelloWorld = "Hello World" };
            var suffix = hoge.GetSuffix();

            switch (hoge)
            {
                case object hogeObj:
                {
                    ((Hoge)hogeObj).TryGetHelloWorld(out var helloWorld);
                    return (helloWorld, 114514, suffix, Math.PI);
                }
            }

            throw new Exception();
        }

        var (h, _, s, _) = HelloWorld();
        Console.WriteLine(h + s);
    }
}