code: def stream_buckets(self, bucket_type=None, timeout=None):
          
          if not self.bucket_stream():
              raise NotImplementedError('Streaming list-buckets is not '
                                        'supported')
          msg_code = riak.pb.messages.MSG_CODE_LIST_BUCKETS_REQ
          codec = self._get_codec(msg_code)
          msg = codec.encode_get_buckets(bucket_type,
                                         timeout, streaming=True)
          self._send_msg(msg.msg_code, msg.data)
          return PbufBucketStream(self, codec)
docs: Stream list of buckets through an iterator