code: def extractIndices(
      index_fields: IndexList,
  ) -> Sequence[tuple[str, Index, Callable[[Any], Any]]]:
      indices = []
      for index_type, predicates in index_fields.items():
          predicate = predicates[0]
          index = predicate.index
          preprocess = predicate.preprocess
          if predicate.index is None:
              index = predicate.initIndex()
          assert index is not None
          indices.append((index_type, index, preprocess))
  
      return indices
  
file_path: dedupe/dedupe/blocking.py
imports: from __future__ import annotations
  import logging
  import time
  from collections import defaultdict
  from typing import TYPE_CHECKING
label_desc: Use image node_id 2 for calling a global function with example usage: extractIndices(index_fields) and returns: indices