Required functionality.

def save(self, obj):
        """Required functionality."""
        if not obj.id:
            obj.id = uuid()

        stored_data = {
            'id': obj.id,
            'value': obj.to_data()
        }

        index_vals = obj.indexes() or {}
        for key in obj.__class__.index_names() or []:
            val = index_vals.get(key, '')
            stored_data[key] = DynamoMappings.map_index_val(val)

        table = self.get_class_table(obj.__class__)
        item = Item(table, data=stored_data)

        item.save(overwrite=True)