iterator coordinator.cs

public class Coordinator<T> {

    private readonly Queue<IEnumerator> _coroutines = new Queue<IEnumerator>();
        
    public Coordinator(IEnumerable<Func<Coordinator<T>, IEnumerator>> coroutines) {

        // add all coroutines to our queue of coroutines to execute
        foreach(var coroutine in coroutines) {
            _coroutines.Enqueue(coroutine(this));
        }
    }

    public void Execute() {

        // iterate over coroutines
        while(_coroutines.Count > 0) {

            // get next coroutine
            var coroutine = _coroutines.Dequeue();
            if(coroutine.MoveNext()) {

                // if MoveNext was true, the coroutine expects to be resumed, so we put the coroutine back in the queue to
                // call MoveNext again once we've given the other coroutines a chance
                _coroutines.Enqueue(coroutine);
            }
        }
    }

    public T State { get; set; }
}