code: def _replace_original_empty_string_with_none(column_series):
      """Replaces original empty string with None"""
      column_series.loc[column_series == "ORIGINAL_NA"] = None
      return column_series
  
file_path: pyjanitor/janitor/functions/currency_column_to_numeric.py
imports: from functools import partial
  from typing import Optional, Union
  import pandas
  import pandas_flavor
  from janitor.utils import check, check_column, deprecated_alias
label_desc: Use image node_id 4 for calling a global function with example usage: _replace_original_empty_string_with_none(column_series) and returns: column_series