using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        foreach (var i in GetAll()) {

            Console.WriteLine(i);

        }

    }

    static IEnumerable<int> GetAll() {

        try {

            return GetAllImpl();

        } catch (Exception) {

            Console.WriteLine("GetAllImpl threw");

            return null;

        }

    }

    static IEnumerable<int> GetAllImpl() {

        yield return 1;

        throw new NotImplementedException();

    }

}