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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_attribute(bucket, query_param, xml_response_tag, retry_params=None, _account_id=None):
 """Helper method to request a bucket parameter and parse the response. Args: bucket: A Google Cloud Storage bucket of form '/bucket'. query_param: The query parameter to include in the get bucket request. xml_response_tag: The expected tag in the xml response. retry_params: An api_utils.RetryParams for this call to GCS. If None, the default one is used. _account_id: Internal-use only. Returns: The xml value as a string. None if the returned xml does not match expected format. Raises: errors.AuthorizationError: if authorization failed. errors.NotFoundError: if the bucket does not exist. """

  api = storage_api._get_storage_api(retry_params=retry_params,
                                     account_id=_account_id)
  common.validate_bucket_path(bucket)
  status, headers, content = api.get_bucket('%s?%s' % (bucket, query_param))

  errors.check_status(status, [200], bucket, resp_headers=headers, body=content)

  root = ET.fromstring(content)
  if root.tag == xml_response_tag and root.text:
    return root.text
  return None