@Override
    public String toString() {
        //return "TDS{" + "listeBloc=" + listeBloc + ", num_bloc=" + num_bloc + ", num_imbrication=" + num_imbrication + ", actuelle=" + region_actuelle + '}';
        String str="";
        Region r;
        Entree e;
        Symbole s;
        for(Entry ent : listeBloc.entrySet()){
            r=(Region) ent.getKey();
            str+="Region "+r.getBloc()+" "+r.getProfondeur()+"\n";
            for(Entry entry : listeBloc.get(r).entrySet()){
                e = (Entree) entry.getKey();
                s = (Symbole) entry.getValue();
                str+="\t"+e.getNom()+"->"+s.toString()+"\n";
            }
            str+="\n";
        }
        return str;
    }