What am I doing wrong with Lavarvel request?

Question

Laravel

1. Route
Route::get('/{lang?}', ['uses' => '[email protected]', 'as' => 'home']);
2. In the controller
use Illuminate\Support\Facades\Request;
public function Index(Request $request)
{
echo "lang = ".Request::input('lang');
}
As a result, an empty string is displayed. I guess that there is some kind of bug in the routing, but where exactly.

Answer 1

Question closed, it dawned on me that {lang?} is not a GET parameter!
As a result, corrected
public function Index($lang) {
echo $lang;
}