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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 get_bucket_policy(self, bucket_name):
 """ Get bucket policy of given bucket name. :param bucket_name: Bucket name. """

        is_valid_bucket_name(bucket_name)

        response = self._url_open("GET",
                                  bucket_name=bucket_name,
                                  query={"policy": ""})
        return response.data