// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002360/guid-notin

​

// @nuget: Z.ExtensionMethods

​

using System;

public class Program

{

    public static void Main()

    {

        Guid guid = Guid.NewGuid();

​

        Guid[] guids = new Guid[]

        {

            Guid.NewGuid(),

            Guid.NewGuid(),

            Guid.NewGuid(),

            guid

        };

​

        // C# Extension Method: Guid - NotIn

        if(guid.NotIn(guids))

        {

            Console.WriteLine("{0} doesn't exists in the list.", guid);

        }

        else

        {

            Console.WriteLine("{0} exists in the list.", guid);

        }

    }

}

​