def storage(self):
        """
        Instantiates and returns a storage instance
        """
        if self.backend == 'redis':
            return RedisBackend(self.prefix, self.secondary_indexes)
        if self.backend == 'dynamodb':
            return DynamoDBBackend(self.prefix, self.key, self.sort_key,
                                   self.secondary_indexes)
        return DictBackend(self.prefix, self.secondary_indexes)
Instantiates and returns a storage instance