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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(self, data):
 """ First fit a transformer using the SFrame `data` and then return a transformed version of `data`. Parameters data : SFrame The data used to fit the transformer. The same data is then also transformed. Returns ------- Transformed SFrame. See Also -------- transform, fit_transform Notes ----- - The default implementation calls fit() and then calls transform(). You may override this function with a more efficient implementation." Examples -------- .. sourcecode:: python >> transformed_sf = chain.fit_transform(sf) """

        if not self._transformers:
            return self._preprocess(data)

        transformed_data = self._preprocess(data)
        final_step = self._transformers[-1]
        return final_step[1].fit_transform(transformed_data)