using System;

using System.Collections;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Start");

        IEnumerator eenum = TestA();

        while(eenum.MoveNext()){}

    }

    public static IEnumerator TestA()

    {

        Console.WriteLine("TestA");

        yield return TestB().MoveNext();

        yield return TestB().MoveNext();

        Console.WriteLine("After TestA Call TestB");

        yield return null;

    }

    public static IEnumerator TestB()

    {

        yield return null;

        Console.WriteLine("TestB");

        yield break;

        Console.WriteLine("After TestB Break");

        yield return null;

    }   

}