def _validate_estimator(self):
        """Check the NN estimators shared across the different SMOTE
        algorithms.
        """
        self.nn_k_ = check_neighbors_object(
            "k_neighbors", self.k_neighbors, additional_neighbor=1
        )
Check the NN estimators shared across the different SMOTE
        algorithms.
        
imblearn/over_sampling/_smote/base.py