How to display the number of items in a category (add square bracket)

wp_category_number3.php

add_filter('wp_nav_menu_objects','my_nav_count');
function my_nav_count($items){
foreach ($items as $item){
if($item->object == 'category'){
$item->title .= " [". get_term($item->object_id,'category')->count ."]";
$args[] = $item;
}
}
return $args;
}