using System.Collections.Generic;
public static void Main()
var l = new List<int>(){1,2,3,4,5};
l = l.Multiply(x => x%2 == 0, 10);
Console.Write(String.Join(",", l));
public static class ListExtensions{
public delegate bool IsEqual(int x);
public static List<int> Multiply(this IEnumerable<int> list, IsEqual func, int multiply){
List<int> newList = new List<int>();