public Set<E> edges() {
        List<V> verts = new LinkedList<V>();
        verts.addAll(this.vertices);
        Set<E> alledges = new HashSet<E>();
        for (int i=0;i<verts.size();i++){
            V v = verts.get(i);
            alledges.addAll(this.outgoingEdges(v));
        }
        return alledges;
    }