code: def test_contains_na_kwarg_for_nullable_string_dtype(
      nullable_string_dtype, na, expected, regex
  ):
      # https://github.com/pandas-dev/pandas/pull/41025#issuecomment-824062416
  
      values = Series(
          ["a", "b", "c", "a", np.nan], dtype=nullable_string_dtype
      )
      result = values.str.contains("a", na=na, regex=regex)
      expected = Series(
          [True, False, False, True, expected], dtype="boolean"
      )
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime
  import re
  import numpy
  import pytest
  from pandas.errors import PerformanceWarning
  import pandas.util._test_decorators
  import pandas
  from pandas import Series, _testing
  from pandas.tests.strings import _convert_na_value, object_pyarrow_numpy
label_desc: Use image node_id 5 for calling a global function with example usage: test_contains_na_kwarg_for_nullable_string_dtype(nullable_string_dtype, na, expected, regex) without return types