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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 cancel(self):
 """ Forget about the changes """

        logger.info("Index: Index update cancelled")
        if self.index_writer:
            self.index_writer.cancel()
            del self.index_writer
        self.index_writer = None
        if self.label_guesser_updater:
            self.label_guesser_updater.cancel()
        self.label_guesser_updater = None