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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 unscan(self):
 """ Undo the last scan, resetting the position and match registers. 0 2 'st string' 0 'test string' """

        self.pos_history.pop()
        self._pos = self.pos_history[-1]
        self.match_history.pop()
        self._match = self.match_history[-1]