code: def get_neighbour_keys(self, hash_name, bucket_key):
          
          # get the permutedIndex given hash_name
          permutedIndex = self.permutedIndexs[hash_name]
          # return neighbour bucket keys of query bucket key
          return permutedIndex.get_neighbour_keys(
              bucket_key,
              permutedIndex.num_neighbour)
docs: Return the neighbour buckets given hash_name and query bucket key.