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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 fit_transform_with(self, estimator, out_ds, fmt=None):
 """Create a new dataset with the given estimator. The estimator will be fit by this dataset, and then each trajectory will be transformed by the estimator. Parameters estimator : BaseEstimator This object will be fit and used to transform this dataset into a new dataset. out_ds : str or Dataset This dataset will be transformed and saved into out_ds. If out_ds is a path, a new dataset will be created at that path. fmt : str The type of dataset to create if out_ds is a string. Returns ------- out_ds : Dataset The transformed dataset. Examples -------- diheds = dataset("diheds") tica = diheds.fit_transform_with(tICA(), 'tica') kmeans = tica.fit_transform_with(KMeans(), 'kmeans') msm = kmeans.fit_with(MarkovStateModel()) """

        self.fit_with(estimator)
        return self.transform_with(estimator, out_ds, fmt=fmt)