using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var list = new List<int>();

        for (var i = 1; i <= 10; i++)

        {

            list.Add(i);

        }

        var messages = GetMessages(list).ToList();

        Write(messages);

    }

    private static IEnumerable<string> GetMessages(IEnumerable<int> list)

    {

        foreach (var val in list)

        {

            Console.WriteLine($"Ready to return {val}");

            yield return $"Value: {val}";

            Console.WriteLine($"Returned {val}");

            if (val % 2 == 0)

            {

                Console.WriteLine($"Ready to return even {val}");

                yield return $"Even value: {val}";

                Console.WriteLine($"Returned even value {val}");

            }

        }

        Console.WriteLine("Acabou");

    }

    private static void Write(IEnumerable<string> messages)

    {

        foreach (var message in messages)

        {

            Console.WriteLine(message);

        }

    }

}