code: def test_str_accessor_in_apply_func():
      # https://github.com/pandas-dev/pandas/issues/38979
      df = DataFrame(zip("abc", "def"))
      expected = Series(["A/D", "B/E", "C/F"])
      result = df.apply(lambda f: "/".join(f.str.upper()), axis=1)
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  from pandas import DataFrame, Index, MultiIndex, Series
  import pandas._testing
  from pandas.core.strings.accessor import StringMethods
  from pandas.tests.strings import object_pyarrow_numpy
label_desc: Use image node_id 43 for calling a global function with example usage: test_str_accessor_in_apply_func() without return types