Simulating app.Run with app.Use in ASP.NET Core 2

startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace MiddlewareDemo
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            ////--- Default app.Run usage ----------------------------
            // app.Run(async (context) =>
            // {
            //     await context.Response.WriteAsync("Hello World! 0");
            // });            

            ////--- Default app.Use - short-cricuit--------------------
            app.Use(async (context, next) =>
            {
                await context.Response.WriteAsync("Hello World! 1");
            });            

            ////--- simulating app.Run with a handler -----------------
            // RequestDelegate handler=async (context) =>
            // {
            //     await context.Response.WriteAsync("Hello World! 2");
            // };
            // app.Use(_ => handler);            

            ////--- simulating app.Run with an anonymous function------
            // app.Use(_ => async (context) =>
            // {
            //     await context.Response.WriteAsync("Hello World! 3");
            // });
        }
    }
}