using System;

     //Chicken implements the Ibrid class

    //Chicken lays an egg that will hatch into a new chicken

    //Eggs from other types of birds should hatch into a new bird of their parent type

    //Hatching an egg for the 2nd time throws a system.invalidoperationexception

​

    public interface IBird

    {

        Egg Lay();

    }

​

    // Should implement IBird

    public class Chicken : IBird

    {

        public Chicken()

        {

        }

​

        public Egg Lay()

        {

            return new Egg(() => new Chicken());

        }

    }

​

    public class Egg

    {

        private Func<IBird> hatchBirdFunc;

        private bool hasHatched = false;

​

        public Egg(Func<IBird> createBird)

        {

            hatchBirdFunc = createBird;

            hasHatched = false;

        }

​

        public IBird Hatch()

        {

            if (!hasHatched)

            {

                hasHatched = true;

                return hatchBirdFunc.Invoke();

            }

            throw new InvalidOperationException();

        }

    }

​

    public class Hatchery

    {

        public static void Main(string[] args)

        {

            var chicken1 = new Chicken();

            var egg = chicken1.Lay();

            var childChicken = egg.Hatch();

            var childChicken2 = egg.Hatch(); //-- should throw an error

        }

    }