Required functionality.

def find_one(self, cls, id):
        """Required functionality."""
        try:
            db_result = self.get_class_table(cls).lookup(id)
        except ItemNotFound:
            # according to docs, this shouldn't be required, but it IS
            db_result = None

        if not db_result:
            return None

        obj = cls.from_data(db_result['value'])
        return obj