code: def data_for_grouping():
      return Categorical(["a", "a", None, None, "b", "b", "a", "c"])
  
imports: import string
  import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  import pandas
  from pandas import Categorical
  import pandas._testing
  from pandas.api.types import CategoricalDtype
  from pandas.tests.extension import base
label_desc: Use image node_id 7 for calling a global function with example usage: data_for_grouping() and returns: Categorical