code: def _convert_keys(
      self, d: Optional[Dict[str, Any]]
  ) -> Dict[str, Any]:
      if d is None:
          return {}
      file_parser = self.file_parser
      recognizer = self.recognizer
      if file_parser is None or recognizer is None:
          return d
      mapping = recognizer.index_mapping
      header = file_parser.feature_header
      header2str_idx = {name: str(i) for i, name in enumerate(header)}
      return {str(mapping[header2str_idx[k]]): v for k, v in d.items()}
  
imports: import numpy
  from enum import Enum
  from typing import Any
  from typing import Dict
  from typing import List
  from typing import Optional
  from dataclasses import dataclass
  from cftool.misc import safe_execute
  from cftool.misc import shallow_copy_dict
  from cftool.array import normalize
  from cftool.array import normalize_from
  from cftool.array import recover_normalize_from
  from cftool.array import min_max_normalize
  from cftool.array import min_max_normalize_from
  from cftool.array import recover_min_max_normalize_from
  from cftool.array import quantile_normalize
  from cftool.array import quantile_normalize_from
  from cftool.array import recover_quantile_normalize_from
  from .file import FileParserBlock
  from .recognizer import RecognizerBlock
  from ....schema import DataBundle
  from ....schema import ColumnTypes
  from ....schema import INoInitDataBlock
label_desc: Use image node_id 7 for calling the PreProcessorBlock obj's underlying member method code with example usage: obj._convert_keys(d) and returns: unknown, dict, d