code: def is_sklearn_estimator(obj):
      """Check whether obj is an sklearn estimator.
  
      Parameters
      ----------
      obj : any class or object
  
      Returns
      -------
      is_sklearn_est : bool, whether obj is an sklearn estimator (class or instance)
      """
      if not isclass(obj):
          obj = type(obj)
  
      is_in_sklearn = issubclass(obj, SklearnBaseEstimator)
      is_in_sktime = issubclass(obj, BaseObject)
  
      is_sklearn_est = is_in_sklearn and not is_in_sktime
      return is_sklearn_est
  
file_path: sktime/sktime/utils/sklearn/_scitype.py
imports: from inspect import isclass
  from sklearn.base import BaseEstimator
  from sklearn.base import ClassifierMixin, ClusterMixin, RegressorMixin, TransformerMixin
  from sklearn.model_selection import GridSearchCV, RandomizedSearchCV
  from sklearn.pipeline import Pipeline
  from sktime.base import BaseObject
label_desc: Use image node_id 1 for calling a global function with example usage: is_sklearn_estimator(obj) and returns: is_sklearn_est