function is_admin_page() {
        return

        //We need to check if there is in fact the page index inside $_GET global variable
        isset($_GET['page']) && (
        strpos($_GET['page'], 'newsletter_') === 0 ||
        strpos($_GET['page'], 'newsletter-statistics/') === 0 ||
        strpos($_GET['page'], 'newsletter/') === 0 ||
                strpos($_GET['page'], 'newsletter-updates/') === 0 ||
        strpos($_GET['page'], 'newsletter-flows/') === 0
        );
    }