using System;

public class Program

{

    class Prout {

        public bool IsBool {get;set;}

    }

    public static void Main()

    {

        Prout prout = null;

        if (prout?.IsBool == false){

            Console.WriteLine("Object is null, bool value is false");

        } else {

            Console.WriteLine("Object is null, bool value is true");

        }

        prout = new Prout();

        if (prout?.IsBool == false){

            Console.WriteLine("Object is not null, bool value is false");

        } else {

            Console.WriteLine("Object is not null, bool value is true");

        }

        prout.IsBool = false;

        if (prout?.IsBool == false){

            Console.WriteLine("Object is not null, bool value set to false, bool value is false");

        } else {

            Console.WriteLine("Object is not null, bool value set to false, bool value is true");

        }

        prout.IsBool = true;

        if (prout?.IsBool == false){

            Console.WriteLine("Object is not null, bool value set to true, bool value is false");

        } else {

            Console.WriteLine("Object is not null, bool value set to true, bool value is true");

        }

    }

}