using System;

using System.Text;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public void Main()

    {

        var log = new StringBuilder();

        foreach (var number in GetEnumerable(log))

        {

            log.AppendLine(number.ToString());

        }

        Console.WriteLine(log);

    }

​

    public static IEnumerable<int> GetEnumerable(StringBuilder log)

    {

        using (var context = new Context(log))

        {

            foreach (var i in Enumerable.Range(1, 5))

            {

                yield return i;

            }

        }

    }

}

​

public class Context : IDisposable

{

    private readonly StringBuilder log;

    public Context(StringBuilder log)

    {

        this.log = log;

        this.log.AppendLine("Context created");

    }

​

    public void Dispose()

    {

        this.log.AppendLine("Context disposed");

    }

}