function example(): void {
    using $file = File\open_read_only("example.txt") {
        // $file is present here
    }

    // $file is destroyed here

    using $user = Users\by_id($user_id), $articles = Articles\by_user($user_id) {
        // $user and $articles are present here
    }

    // $user and $articles are destroyed here

    using $user = Users\by_id($id) if $user is nonnull {
        // $user is present here
    }

    // $user is destroyed here
}