public List<Link<T>> getAllLinks() {
        for (int i = 0; i < graph_nodes.getLength(); i++)
           for (int j = 0; j < ((GraphNode) graph_nodes.get(i)).getLinks().getLength();j++)
               aristas.append(((Link) ((GraphNode) graph_nodes.get(i)).getLinks().get(j)));//adds all existing links of each node to the list.

        return aristas;
    }