code: def test_empty_input():
      """Checks empty input is processed properly."""
      assert _currency_column_to_numeric("") == "ORIGINAL_NA"
  
file_path: pyjanitor/tests/functions/test_currency_column_to_numeric.py
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from janitor.functions.currency_column_to_numeric import _currency_column_to_numeric
label_desc: Use image node_id 10 for calling a global function with example usage: test_empty_input() without return types