Required functionality.

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

        index_names = obj.__class__.index_names() or []
        index_dict = obj.indexes() or {}
        index_name_values = [
            (key, index_dict.get(key, ''))
            for key in index_names
        ]

        write_rec(
            obj.__class__.get_table_name(),
            obj.id,
            obj.to_data(),
            index_name_values
        )