docstr: Check fitted status and return a Boolean value.
code: def __sklearn_is_fitted__(self):
      """
      Check fitted status and return a Boolean value.
      """
      return hasattr(self, "_is_fitted") and self._is_fitted
  
file_path: scikit-learn/examples/developing_estimators/sklearn_is_fitted.py
imports: from sklearn.base import BaseEstimator, ClassifierMixin
  from sklearn.utils.validation import check_is_fitted
label_desc: Use image node_id 5 for calling the CustomEstimator obj's underlying member method code with example usage: obj.__sklearn_is_fitted__() and returns: unknown