using System;

using System.Collections.Generic;

​

public class Program

{

​

    public static void Main(string[] args)

    {

        void treatUser (User user)  { 

            if (user.Label == "A")  {

                DoThis(user);

            }

            else {

                DoThat(user);   

            }

        }

        List<User> users = new List<User>()

        {

            new User() { Id = 1, Label = "A" },

            new User() { Id = 2, Label = "A" },

            new User() { Id = 3, Label = "B" },

            new User() { Id = 4, Label = "B" }

        };

​

      users.ForEach(treatUser);

    }

​

    static void DoThis(User user)

    {

        Console.WriteLine("dothis " + user.Label);

    }

​

    static void  DoThat(User user)

    {

        Console.WriteLine("dothat " + user.Label);

    }

}

​

class User

{

    public int Id { get; set; }

    public string Label { get; set; }

}

​

​