def pre_save(self, model_instance, add):
        value = getattr(model_instance, self.attname)
        if value is None:
            return None

        return self._map(lambda item: self.item_field_type.pre_save(_FakeModel(self.item_field_type, item), add), value)
Gets our value from the model_instance and passes its items
dataset/ETHPy150Open potatolondon/djangae/djangae/fields/iterable.py/IterableField.pre_save