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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def kfold(self, k=5, stratify=False, shuffle=True, seed=33):
 """K-Folds cross validation iterator. Parameters k : int, default 5 stratify : bool, default False shuffle : bool, default True seed : int, default 33 Yields ------- X_train, y_train, X_test, y_test, train_index, test_index """

        if stratify:
            kf = StratifiedKFold(n_splits=k, random_state=seed, shuffle=shuffle)
        else:
            kf = KFold(n_splits=k, random_state=seed, shuffle=shuffle)

        for train_index, test_index in kf.split(self.X_train, self.y_train):
            X_train, y_train = idx(self.X_train, train_index), self.y_train[train_index]
            X_test, y_test = idx(self.X_train, test_index), self.y_train[test_index]
            yield X_train, y_train, X_test, y_test, train_index, test_index