DelarationAndDeconstruction.cs

#nullable enable

using System;

Err err;

// Note that we can now mix declaration and tuple deconstruction
(var ret1, err) = GetAnswer();
if (err == null) Console.WriteLine(ret1);

// Go-like error handling anybody?
(var ret2, err) = GetAnswer_Error();
if (err != null) Console.WriteLine(err);

(int?, Err?) GetAnswer() => (42, null);
(int?, Err?) GetAnswer_Error() => (null, new());

class Err { public string Message => "Error"; }