"Class 'App\Models\UserModel' not found"

use App\Models\UserModel; must be defined before class Auth {

PHP Code:

<?php
namespace App\Libraries;

use App\Models\UserModel;

class Auth {
    
    public function __construct()
    {
      if ($_SESSION['loggedIn'] == true) {
           // you can use
          $userModel = new UserModel();
          $user = $userModel->find($_SESSION['login_id']);
.......
      }
    }
}