public static function set_for_current_order_only_show_countries(array $a) { if (count(self::$for_current_order_only_show_countries)) { //we INTERSECT here so that only countries allowed by all forces (modifiers) are added. self::$for_current_order_only_show_countries = array_intersect($a, self::$for_current_order_only_show_countries); } else { self::$for_current_order_only_show_countries = $a; } }