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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 redo(self):
 """Redo the last action. This will call `redo()` on all controllers involved in this action. """

        controllers = self.forward()
        if controllers is None:
            ups = ()
        else:
            ups = tuple([controller.redo() for
                         controller in controllers])
        if self.process_ups is not None:
            return self.process_ups(ups)
        else:
            return ups