code: def test_sanitize_boolean_dtype():
      df = pd.DataFrame(
          {
              "bool_none": pd.array(
                  [True, False, None], dtype="boolean"
              ),
              "none": pd.array([None, None, None], dtype="boolean"),
              "bool": pd.array([True, False, True], dtype="boolean"),
          }
      )
  
      df_clean = sanitize_dataframe(df)
      assert {col.dtype.name for _, col in df_clean.items()} == {
          "object"
      }
  
      result_python = {
          col_name: list(col) for col_name, col in df_clean.items()
      }
      assert result_python == {
          "bool_none": [True, False, None],
          "none": [None, None, None],
          "bool": [True, False, True],
      }
  
file_path: altair/tests/utils/test_utils.py
imports: import io
  import json
  import warnings
  import numpy
  import pandas
  import pytest
  from altair.utils import infer_vegalite_type, sanitize_dataframe
label_desc: Use image node_id 9 for calling a global function with example usage: test_sanitize_boolean_dtype() without return types