template<class T>
void List_vector< T >::canc_elemL1_from_listL2(const List_vector<T>& Lista2){
    position pos;
    position pos_l2;

    pos = begin();
    pos_l2 = Lista2.begin();

   // cout << Lista2.read(pos_l2) << endl;

    while(!end(next(pos))){ //cout << read(pos) << endl;
        while(!end(next(pos_l2))){ //cout << Lista2.read(pos_l2) << endl;
            if(read(pos) == Lista2.read(pos_l2))
                                                erase(pos);
            pos_l2 = next(pos_l2);
        }
    pos = next(pos);
    pos_l2 = Lista2.begin();
    }
}