my code
public function registerAutoloaders(DiInterface $di = null)
{
$loader = new Loader();
$loader->registerNamespaces(
[
'Modules\Backend\Controllers' => __DIR__ . '/controllers/',
'Modules\Backend\Models' => __DIR__ . '/models/',
'Modules\Backend\Views' => __DIR__ . '/views/',
]
);
$loader->register();
}