class_docstr: Base class for indexing
class_docstr_tok: ["Base","class","for","indexing"]
docstr: Serialize the index on disk
docstr_tok: ["Serialize","the","index","on","disk"]
code: def save(self, file: Union[str, PurePath]):
      """Serialize the index on disk"""
      raise NotImplementedError
  
imports: import importlib.util
  import os
  import tempfile
  from pathlib import PurePath
  from typing import TYPE_CHECKING, Dict, List, NamedTuple, Optional, Union
  import fsspec
  import numpy
  from .utils import logging
  from .utils import tqdm
label_desc: Use image node_id 3 for calling the BaseIndex obj's underlying member method code with example usage: obj.save(file) without return types