using System;

using System.Collections.Generic;

public class Program

{

    static IList<int> P(IList<int> list) 

    {

        list.Add(2);

        return list;

    }

​

    public static void Main()

    {

        var a = new[] { 1, 2, 3 };

​

        var b = P(a);

​

        Console.WriteLine(a == b);  

    }

}