code: def test_cat_accessor_api(self):
      # GH#9322
  
      assert Series.cat is CategoricalAccessor
      ser = Series(list("aabbcde")).astype("category")
      assert isinstance(ser.cat, CategoricalAccessor)
  
      invalid = Series([1])
      with pytest.raises(
          AttributeError, match="only use .cat accessor"
      ):
          invalid.cat
      assert not hasattr(invalid, "cat")
  
file_path: pandas/pandas/tests/series/accessors/test_cat_accessor.py
imports: import numpy
  import pytest
  from pandas import Categorical, DataFrame, Index, Series, Timestamp, date_range, period_range, timedelta_range
  import pandas._testing
  from pandas.core.arrays.categorical import CategoricalAccessor
  from pandas.core.indexes.accessors import Properties
label_desc: Use image node_id 3 for calling the TestCatAccessor obj's underlying member method code with example usage: obj.test_cat_accessor_api() without return types