class_docstr: Add indexing features to `datasets.Dataset`
class_docstr_tok: ["Add","indexing","features","to","`","datasets.Dataset","`"]
code: def _check_index_is_initialized(self, index_name: str):
      if not self.is_index_initialized(index_name):
          raise MissingIndex(
              f"Index with index_name '{index_name}' not initialized yet. Please make sure that you call `add_faiss_index` or `add_elasticsearch_index` first."
          )
  
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 5 for calling the IndexableMixin obj's underlying member method code with example usage: obj._check_index_is_initialized(index_name) without return types