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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 _ndays(self, start_date, ndays):
 """ Compute an end date given a start date and a number of days. """

        if not getattr(self.args, 'start-date') and not self.config.get('start-date', None):
            raise Exception('start-date must be provided when ndays is used.')

        d = date(*map(int, start_date.split('-')))
        d += timedelta(days=ndays)

        return d.strftime('%Y-%m-%d')