using System;

​

public static class MyExtensions

{

    public static bool IsNullOrLarge(this string val)

    {

        if (val == null) return true;

        if (val.Length > 10) return true;

        return false;

    }

}

​

public class Program

{   

    public static void Main()

    {

        var x = "legal";

        Console.WriteLine($"this should be false: {x.IsNullOrLarge()}");

        string y = null;

        Console.WriteLine($"I thought this would throw! but it works and prints true: {y.IsNullOrLarge()}");

    }

}