docstr: Last step of creating the indexed dataset.
  Flush and close the binary file.
  Finalizing the index file by using the aggregated document size information.
docstr_tok: ["Last","step","of","creating","the","indexed","dataset",".","Flush","and","close","the","binary","file",".","Finalizing","the","index","file","by","using","the","aggregated","document","size","information","."]
code: def finalize(self, index_file):
      """
      Last step of creating the indexed dataset.
      Flush and close the binary file.
      Finalizing the index file by using the aggregated document size information.
      """
      self._data_file.close()
  
      with MMapRetrievalIndexedDataset.Index.writer(
          index_file, self._dtype, self.retrieval_db
      ) as index:
          index.write(self._sizes, self.chunk_size, stride=self.stride)
  
imports: import os
  import shutil
  import struct
  from functools import lru_cache
  from itertools import accumulate
  from typing import List
  import numpy
  import torch
  from nemo.utils import logging
label_desc: Use image node_id 5 for calling the MMapRetrievalIndexedDatasetBuilder obj's underlying member method code with example usage: obj.finalize(index_file) without return types