class MolecularFormulaRange implements Cloneable {

    public Iterable<IIsotope> isotopes() {
        return new Iterable<IIsotope>() {

            @Override
            public Iterator<IIsotope> iterator() {
                return isotopesMax.keySet().iterator();
            }
        };
    }

    public  MolecularFormulaRange();

}