code: def stream_buckets(self, bucket_type=None, timeout=None):
          
          if not self.bucket_stream():
              raise NotImplementedError('Streaming list-buckets is not '
                                        "supported on %s" %
                                        self.server_version.vstring)
          bucket_type = self._get_bucket_type(bucket_type)
          url = self.bucket_list_path(bucket_type=bucket_type,
                                      buckets="stream", timeout=timeout)
          status, headers, response = self._request('GET', url, stream=True)
  
          if status == 200:
              return HttpBucketStream(response)
          else:
              raise RiakError('Error listing buckets.')
docs: Stream list of buckets through an iterator