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

namespace Mww66
{
    class Program
    {
        static void Main(string[] args)
        {
            IEnumerable<int> result = from value in Enumerable.Range(0, 100)
                                      select value;

            List<string> elements = new List<string> { "cat", "dog", "bird" };
            List<int> ielements = new List<int> { 1,2,3 };
            foreach (var value in elements)
            {
                //Console.WriteLine(value);
            }

            System.Console.WriteLine(elements.IsEmpty());
            System.Console.WriteLine(result.Mean());

            System.Console.ReadKey();
        }
    }

    public static class IenumerableExtend
    {
        public static bool IsEmpty<T>(this IEnumerable<T> input)
        {
            return input != null && input.Any();
        }

        public static int Mean(this IEnumerable<int> input)
        {
            int x = 3;
            return x;
        }
        public static void Mean(this IEnumerable<float> input)
        {
            //
        }

        public static void MeanLength(this IEnumerable<string> input)
        {
            //
        }
    }
}