code: def get_partition_hash(self):
          
          if self.has_partition_hash():
              return unpack_from(FMT_BE_INT, self._buffer, PARTITION_HASH_OFFSET)[0]
          return self.hash_code()
docs: Returns partition hash calculated for serialized object.
              Partition hash is used to determine partition of a Data and is calculated using
                  * PartitioningStrategy during serialization.
                  * If partition hash is not set then hash_code() is used.
  
          :return: partition hash