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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 save(self, model_fname='model.pkl'):
 """Save the state of the IncrementalModel in a pickle file. Parameters model_fname : Optional[str] The name of the pickle file to save the state of the IncrementalModel in. Default: model.pkl """

        with open(model_fname, 'wb') as fh:
            pickle.dump(self.stmts, fh, protocol=4)