public void transfer(int fromCode, int toCode, int date, double value)
            throws InvalidCode, InvalidValue {
        if (!accounts.containsKey(fromCode) || !accounts.containsKey(toCode)) {
            throw new InvalidCode();
        }

        double s = accounts.get(fromCode).getValue();

        //if (s > accounts.get(toCode).getValue()) {
        if (value > s){
        throw new InvalidValue();
        } else {
            double t = accounts.get(toCode).getValue();
            t += s;

        }