code: def factors(self):
          
          if self._factors is None:
              self._factors = FactorList(
                  self._version,
                  service_sid=self._solution['service_sid'],
                  identity=self._solution['identity'],
              )
          return self._factors
docs: Access the factors
  
          :returns: twilio.rest.authy.v1.service.entity.factor.FactorList
          :rtype: twilio.rest.authy.v1.service.entity.factor.FactorList