using System;

​

public class Program

{

    public enum Test

    {

        A,

        B

    }

​

    public static void Main()

    {

        Console.WriteLine(Foo(Test.A));

        Console.WriteLine(Foo(Test.B));

        Console.WriteLine(Foo((Test)2));

    }

​

    public static string Foo(Test t) => t switch

    {

        Test.A => "A",

        Test.B => "B"

    };

}