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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 restore(self):
 """ Reset the active WCS keywords to values stored in the backup keywords. """

        # If there are no backup keys, do nothing...
        if len(list(self.backup.keys())) == 0:
            return
        for key in self.backup.keys():
            if key != 'WCSCDATE':
                self.__dict__[self.wcstrans[key]] = self.orig_wcs[self.backup[key]]

        self.update()