How to find source code of Laravel 8 Illuminate API methods?

Question

Let's say I want to know what happens when I add a new Route in Laravel 8 like this:

Route::get('/', function () {
    return view('welcome');
});

I go to the folder vendor/laravel/framework/src/Illuminate/Support/Facades/Route.php and I see:

 * @method static \Illuminate\Routing\Route get(string $uri, array|string|callable|null $action = null)

How does "* @method" syntax work? Where is the code? What am I missing? Thank you