Laravel 5.4 has no Middleware / Authenticate.php

Searching for a bit more about middleware in Laravel, I found the command to create a middleware that is php artisan make: middleware Authenticate , however, this command creates the file only with the handle it does not know the implementation (rsrsrsr), for my luck I had an implementation of another system that I will leave here the source as an example if anyone else needs (modify if necessary!).

Middleware / Authenticate.php:

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Contracts\Auth\Guard;

class Authenticate
{

    /**
    * The Guard implementation.
    *
    * @var Guard
    */
   protected $auth;

   /**
    * Create a new filter instance.
    *
    * @param  Guard  $auth
    * @return void
    */
   public function __construct(Guard $auth)
   {
           $this->auth = $auth;
   }

    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        if ($this->auth->guest())
        {
                if ($request->ajax())
                {
                        return response('Unauthorized.', 401);
                }
                else
                {
                        return redirect()->guest('auth/login');
                }
        }
        return $next($request);
    }
}