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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)