$categories = $this->page->get_categories();
foreach ($categories as $key=>$value)
{
$sub_categories[$value['category_id']] = $this->page->get_sub_categories($value['category_id']);
}
$categories = $this->page->get_categories();
foreach ($categories as $key=>$value)
{
$sub_categories[$value['category_id']] = $this->page->get_sub_categories($value['category_id']);
}