How to start session globally?

PHP Code:

namespace App\Controllers;
use App\Models\Modeloejemplo;
class Demo extends BaseController
{
public function __construct(){
    parent::__construct();  // <<< YOU MUST CALL THIS!! 


If calling that causes an error you must figure out why and fix it.

Thank you!
Everything is going well, the session is already working, my problem was with the redirect.
I am sorry I did not notice it, but thank you very much for the comments!