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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 revert(self, version, url):
 """ Set the given version to be the active draft. This is done by calling the object's `make_draft` method. Logs the revert as a 'save' and messages the user. """

        message = "Draft replaced with %s version. This revert has not been published." % version.date_published
        version.make_draft()

        # Log action as a save
        self.log_action(self.object, CMSLog.SAVE, url=url)
        return self.write_message(message=message)