code: def revert(self, version, url):
          
          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)
docs: 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.