Use drupal_static() instead of plain static keywork to help overriding URLs in other modules

We want to change the list of URL appearing at bottom of print pages and PDF. Especially we want to remove URLs linking to Drupal admin pages while page is printing or preparing PDF while logged in as admin.

hook_print_url_list_alter() is not useful to remove URLs.

I see function _print_friendly_urls() keeping URLs in a static variable and I thought to manipulate that variable in a hook_preprocess_print_url_list() implementation, but I can't with that current code using plan static variable. If it is using drupal_static() then it is possible to get that same static variable by passing function name, _print_friendly_urls, to drupal_static().