code: def test_get_bounds(idx):
      ser = Series(["1_2_3_4_5", "6_7_8_9_10", "11_12"])
      result = ser.str.split("_").str.get(idx)
      expected = Series(["3", "8", np.nan], dtype=object)
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime
  import re
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series, _testing
  from pandas.tests.strings import _convert_na_value, object_pyarrow_numpy
label_desc: Use image node_id 46 for calling a global function with example usage: test_get_bounds(idx) without return types