EventsAndLINQ.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EventsApp
{
    public class MyButton
    {
        public event Action<bool> OnClick;

        public void Clicked()
        {
            if (OnClick != null)
            {
                this.OnClick(true);
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            void adjacentProducts(IEnumerable<int> vals)
            {
                var newVals = 
                    vals.Zip(vals.Skip(1), (x, y) => x * y);

                for (int i = 1; i < vals.Count(); ++i)
                {
                    Console.WriteLine(vals.ElementAt(i - 1) * vals.ElementAt(i));
                }

                foreach (var v in newVals)
                    Console.WriteLine($"{v}");
            }

            adjacentProducts(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

            void myFunction(bool myBool)
            {
                Console.WriteLine("In a handler");
            }

            MyButton b = new MyButton();

            b.Clicked();

            b.OnClick += myFunction;
            b.OnClick += aBool => Console.WriteLine("Another event Handler");

            // Pretend that a button was pressed
            b.Clicked();

            b.OnClick -= myFunction;

            b.Clicked();
        }
    }
}