using System;

​

public class C {

    public static void Main()

    {       

          using(var b = new book()){

        }

    }   

​

    struct book: IDisposable{

        public void Dispose(){

            Console.WriteLine(IsBoxed(this));

        }

    }

public static bool IsBoxed<T>(T value)

{

    return 

        (typeof(T).IsInterface || typeof(T) == typeof(object)) &&

        value != null &&

        value.GetType().IsValueType;

}

}