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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 set_total_duration(self, duration):
 """ Set the total task duration in minutes. """

        if duration < 1:
            raise ValueError(u'Duration must be postive')

        elif self.duration > duration:
            raise ValueError(u'{0} must be greater than current duration')

        self._total_duration = duration