code: def test_is_sklearn_estimator_negative(estimator):
      """Test that is_sklearn_estimator recognizes negative examples correctly."""
      msg = (
          f"is_sklearn_estimator incorrectly considers {estimator.__name__} "
          f"as an sklearn estimator (output True), but output should be False"
      )
      assert not is_sklearn_estimator(estimator), msg
  
file_path: sktime/sktime/utils/sklearn/tests/test_sklearn_typing.py
imports: import pytest
  from sklearn.cluster import KMeans
  from sklearn.neighbors import KNeighborsClassifier, KNeighborsRegressor
  from sklearn.preprocessing import StandardScaler
  from sktime.classification.feature_based import SummaryClassifier
  from sktime.forecasting.naive import NaiveForecaster
  from sktime.utils.sklearn import is_sklearn_estimator, sklearn_scitype
label_desc: Use image node_id 2 for calling a global function with example usage: test_is_sklearn_estimator_negative(estimator) without return types