public void supprimer(int debut, int fin) {
        if (debut == fin && debut > 0) {
            contenu.deleteCharAt(debut - 1);
            position = debut - 1;
        } else if (debut == fin) {
            if (debut > 0) {
                contenu.deleteCharAt(debut);
                position = debut;
            }
        } else if (debut >= 0 && fin >= 0) {
            contenu.delete(debut, fin);
            position = debut;
        }
        notifier();
    }