code: def test_replace_string_dtype_regex(self):
      # GH#31644
      ser = pd.Series(["A", "B"], dtype="string")
      res = ser.replace(r".", "C", regex=True)
      expected = pd.Series(["C", "C"], dtype="string")
      tm.assert_series_equal(res, expected)
  
imports: import re
  import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  import pandas
  import pandas._testing
  from pandas.core.arrays import IntervalArray
label_desc: Use image node_id 45 for calling the TestSeriesReplace obj's underlying member method code with example usage: obj.test_replace_string_dtype_regex() without return types