itemgetter serializer (needed for namedtuple support)

def save_itemgetter(self, obj):
        """itemgetter serializer (needed for namedtuple support)"""
        class Dummy:
            def __getitem__(self, item):
                return item
        items = obj(Dummy())
        if not isinstance(items, tuple):
            items = (items,)
        return self.save_reduce(operator.itemgetter, items)