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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 clean(self):
        ''' priorDays is required for Generic Repeated Expenses to avoid infinite loops '''
        if not self.priorDays and not self.startDate:
            raise ValidationError(_(
                'Either a start date or an "up to __ days in the past" limit is required ' +
                'for repeated expense rules that are not associated with a venue or a staff member.'
            ))
        super(GenericRepeatedExpense,self).clean()