def warningFlag(self):
        '''
        When viewing individual event registrations, there are a large number of potential
        issues that can arise that may warrant scrutiny. This property just checks all of
        these conditions and indicates if anything is amiss so that the template need not
        check each of these conditions individually repeatedly.
        '''
        if not hasattr(self,'invoice'):
            return True
        if apps.is_installed('danceschool.financial'):
            '''
            If the financial app is installed, then we can also check additional
            properties set by that app to ensure that there are no inconsistencies
            '''
            if self.invoice.revenueNotYetReceived != 0 or self.invoice.revenueMismatch:
                return True
        return (
            self.priceWithDiscount != self.invoice.total or
            self.invoice.unpaid or self.invoice.outstandingBalance != 0
        )
When viewing individual event registrations, there are a large number of potential
        issues that can arise that may warrant scrutiny. This property just checks all of
        these conditions and indicates if anything is amiss so that the template need not
        check each of these conditions individually repeatedly.