code: def get_preflist(self, bucket, key):
          
          if not self.preflists():
              raise NotImplementedError("fetching preflists is not supported.")
          bucket_type = self._get_bucket_type(bucket.bucket_type)
          url = self.preflist_path(bucket.name, key, bucket_type=bucket_type)
          status, headers, body = self._request('GET', url)
  
          if status == 200:
              preflist = json.loads(bytes_to_str(body))
              return preflist['preflist']
          else:
              raise RiakError('Error getting bucket/key preflist.')
docs: Get the preflist for a bucket/key
  
          :param bucket: Riak Bucket
          :type bucket: :class:`~riak.bucket.RiakBucket`
          :param key: Riak Key
          :type key: string
          :rtype: list of dicts