public function isRendered()
    {
        $hasChildren = 0 < count($this->children);

        if (true === $this->rendered || !$hasChildren) {
            return $this->rendered;
        }

        if ($hasChildren) {
            foreach ($this->children as $child) {
                if (!$child->isRendered()) {
                    return false;
                }
            }

            return $this->rendered = true;
        }

        return false;
    }