def _validate_X_predict(self, X):
        if self.estimators_ is None or len(self.estimators_) == 0:
            raise NotFittedError("Estimator not fitted, "
                                 "call `fit` before exploiting the model.")

        return self.estimators_[0]._validate_X_predict(X, check_input=True)
Validate X whenever one tries to predict, apply, predict_proba
dataset/ETHPy150Open scikit-learn/scikit-learn/sklearn/ensemble/forest.py/BaseForest._validate_X_predict