Function app

examples/demo.php:4966–4973

* @template TClass * @param string|null $abstract * @return ($abstract is class-string ? TClass : Container) */

(?string $abstract = null)

 * @return ($abstract is class-string<TClass> ? TClass : Container)
 */
function app(?string $abstract = null): mixed
{
    static $container = null;
    if ($container === null) {
        $container = new Container();
    }
    return $abstract !== null ? $container->make($abstract) : $container;
}

function createUser(string $name, string $email): User
{