code: def test_isin(dtype, fixed_now_ts):
      s = pd.Series(["a", "b", None], dtype=dtype)
  
      result = s.isin(["a", "c"])
      expected = pd.Series([True, False, False])
      tm.assert_series_equal(result, expected)
  
      result = s.isin(["a", pd.NA])
      expected = pd.Series([True, False, True])
      tm.assert_series_equal(result, expected)
  
      result = s.isin([])
      expected = pd.Series([False, False, False])
      tm.assert_series_equal(result, expected)
  
      result = s.isin(["a", fixed_now_ts])
      expected = pd.Series([True, False, False])
      tm.assert_series_equal(result, expected)
  
imports: import operator
  import numpy
  import pytest
  from pandas.compat.pyarrow import pa_version_under12p0
  from pandas.core.dtypes.common import is_dtype_equal
  import pandas
  import pandas._testing
  from pandas.core.arrays.string_arrow import ArrowStringArray, ArrowStringArrayNumpySemantics
label_desc: Use image node_id 41 for calling a global function with example usage: test_isin(dtype, fixed_now_ts) without return types