private LinkedList<E> fusion(LinkedList<E> leftList, LinkedList<E> rightList) {
        LinkedList<E> fusionList = new LinkedList<>();
        int index = 0;
        while (leftList.size() != 0 && rightList.size() != 0) {
            System.out.println("LISTES ;-; : \n"+leftList+" / "+rightList);
            if(leftList.get(0).compareTo(rightList.get(0)) >= 0) {
                if (fusionList.size() == 0) {fusionList.addFirst(rightList.get(0));}
                else { fusionList.add(index, rightList.get(0)); }
                rightList.remove(0);
                index++;
                System.out.println("FUSION IS "+fusionList);
            }
            else if(leftList.get(0).compareTo(rightList.get(0)) < 0) {
                if (fusionList.size() == 0) {fusionList.addFirst(leftList.get(0));}
                else { fusionList.add(index, leftList.get(0)); }
                leftList.remove(0);
                index++;
                System.out.println("FUSION IS "+fusionList);
            }
        }
        fusionList.addAll(leftList);
        fusionList.addAll(rightList);
        System.out.println("end fusion: FUSION IS "+fusionList);
        return fusionList;
    }