public function get_siblings() {
        // Returns a list of the siblings of the current node for display in a flat navigation element. Either
        // the in-page links or the breadcrumb links.
        $siblings = false;

        if ($this->has_siblings()) {
            $siblings = [];
            foreach ($this->parent->children as $child) {
                if ($child->display) {
                    $siblings[] = $child;
                }
            }
        }
        return $siblings;
    }