code: def _normalize_index_columns_in_place(equities,
                                        equity_supplementary_mappings,
                                        futures,
                                        exchanges,
                                        root_symbols):
      
      for frame, column_name in ((equities, 'sid'),
                                 (equity_supplementary_mappings, 'sid'),
                                 (futures, 'sid'),
                                 (exchanges, 'exchange'),
                                 (root_symbols, 'root_symbol')):
          if frame is not None and column_name in frame:
              frame.set_index(column_name, inplace=True)
docs: Update dataframes in place to set indentifier columns as indices.
  
      For each input frame, if the frame has a column with the same name as its
      associated index column, set that column as the index.
  
      Otherwise, assume the index already contains identifiers.
  
      If frames are passed as None, they're ignored.