public function addTaxonomy(PageInterface $page, $page_taxonomy = null)
    {
        if (!$page_taxonomy) {
            $page_taxonomy = $page->taxonomy();
        }

        if (empty($page_taxonomy) || !$page->published()) {
            return;
        }

        /** @var Config $config */
        $config = $this->grav['config'];
        if ($config->get('site.taxonomies')) {
            foreach ((array)$config->get('site.taxonomies') as $taxonomy) {
                if (isset($page_taxonomy[$taxonomy])) {
                    foreach ((array)$page_taxonomy[$taxonomy] as $item) {
                        $this->taxonomy_map[$taxonomy][(string)$item][$page->path()] = ['slug' => $page->slug()];
                    }
                }
            }
        }
    }