code: def test_add_column_iterator_repeat_subtraction(dataframe):
      """Checks `add_column` works as expected when adding a pd Series
      to the column"""
      df = dataframe.add_column("city_pop", dataframe.a - dataframe.a)
      assert df.city_pop.sum() == 0
      assert df.city_pop.iloc[0] == 0
  
file_path: pyjanitor/tests/functions/test_add_column.py
imports: import numpy
  import pandas
  import pytest
  from hypothesis import given, settings
  from hypothesis import strategies
  from pandas.testing import assert_series_equal
  from janitor.testing_utils.strategies import df_strategy
label_desc: Use image node_id 7 for calling a global function with example usage: test_add_column_iterator_repeat_subtraction(dataframe) without return types