Template method wrong fit

class BaseImporter: def run(self): data = self.fetch() self.parse(data) self.persist(self.transform()) def fetch(self): raise NotImplementedError def parse(self, d): raise NotImplementedError def transform(self): raise NotImplementedError def persist(self, r): raise NotImplementedError # many subclasses override only persist(); the algorithm never varies The algorithm skeleton never varies and subclasses only change one step. Which is the better structure?