using System;

namespace ConsoleApp1
{
    public class Program
    {
        static void Main(string[] args)
        {
            var tw = new TopWork();
            tw.Work();
        }
    }

    public class TopWork
    {
        public Work _work;

        public TopWork()
        {
            _work = new Work();
            _work._event += new Work.CompleteHandler(Done1);
            _work._delegate += new Work.CompleteHandler(Done1);
        }

        public void Work()
        {
            _work.JustWork();
        }

        private void Done1(int number)
        {
            Console.WriteLine($"Done1 {number}");
        }
    }
        

    public class Work
    {
        public delegate void CompleteHandler(int number);
        public Work.CompleteHandler _delegate;
        public event Work.CompleteHandler _event;

        public void JustWork()
        {
            _delegate(4);
            _event(4);
        }
    }
}