Lambda expression as a method

class Program
    {
        static void Main(string[] args)
        {
            System.Linq.Expressions.Expression<Func<int, int>> e = x => x * x;
            Console.WriteLine(e);

            int[] numbers = { 2, 3, 4, 5 };
            var squaredNumbers = numbers.Select(x => x * x);
            Console.WriteLine(string.Join(" ", squaredNumbers));


            Action<string> greet = name =>
            {
                string greeting = $"Hello {name}!";
                Console.WriteLine(greeting);
            };
            greet("World");

            greet2("Hello World!");

            Console.ReadKey();
        }

        static Action<string> greet2 = name =>
        {
            string greeting = $"Hello {name}!";
            Console.WriteLine(greeting);
        };
    }