using System;

public class Program

{

    public static void Main()

    {

        SomeClass someObject = null;

        DoSomething(someObject);

    }

    static void DoSomething(SomeClass value)

    {

        if (value == null)

        {

            Console.WriteLine("value is null");

            return;

        }

​

        Console.WriteLine("Do something");

    }

}

​

class SomeClass {}