'''in skopt/learning/forest.py replace criterion name "mse" by "squared_error" '''

    def __init__(self, n_estimators=10, criterion='squared_error', max_depth=None,
                                        .
                                        .
                                        .
                                        .
                                        .
                                        .
        if return_std:
            if self.criterion != "squared_error":
                raise ValueError(
                    "Expected impurity to be 'squared_error', got %s instead"

