using System;

using System.Collections.Generic;

using System.Linq;

​

class Program

{

    static void Main()

    {

        var seq = new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

        var pipe = new Pipe<int>(seq);

        while (true)

        {

            if (!pipe.TryTake(out var v))

                break;

            Console.WriteLine($"Outer enumeration: {v}");

            Process(pipe);

        }

    }

​

    static void Process(Pipe<int> pipe)

    {

        foreach (var v in pipe.Take(3))

            Console.WriteLine($"Inner enumeration: {v}");

    }

}

​

class Pipe<T>

{

    List<T> payload;

    int currIndex = 0;

    public Pipe(IEnumerable<T> seq) => payload = seq.ToList();

    public bool TryTake(out T t)

    {

        if (currIndex >= payload.Count)

        {

            t = default;

            return false;

        }

        else

        {

            t = payload[currIndex];

            currIndex++;

            return true;

        }

    }

​

    public IEnumerable<T> Take(int n)

    {

        var newIndex = Math.Min(currIndex + n, payload.Count);

        var result = payload.Skip(currIndex).Take(newIndex - currIndex);

        currIndex = newIndex;

        return result;

    }

}