public function getAncestryGraph($id)
    {
        $data = $this->getAncestry($id);

        if (count($data) == 0) {
            return [null, null];
        }

        // Create Vertices
        $this->vertices = $this->prepareVertices($data);

        // Create Graph
        $graph = new DirectedGraph();
        foreach ($this->vertices as $vertex) {
            $graph->add_vertex($vertex);
        }

        // Create Relations
        foreach ($data as $content) {
            $graph->create_edge($this->vertices[$content->parent_id], $this->vertices[$content->term_id]);
        }

        return [$this->vertices[$id], $graph];
    }