my @all_itemnumbers = $items->get_column('itemnumber');
my @items_to_show = $items->filter_by_visible_in_opac({ opac => 1, patron => $patron })->as_list;
@hidden_items = array_minus( @all_itemnumbers, @items_to_show );
my @all_itemnumbers = $items->get_column('itemnumber');
my @items_to_show = $items->filter_by_visible_in_opac({ opac => 1, patron => $patron })->as_list;
@hidden_items = array_minus( @all_itemnumbers, @items_to_show );