driver.go
func RegisterDriver(d Driver, knownNames ...string) {
	for _, k := range knownNames {
		drivers[strings.ToLower(k)] = d
	}
	log.Info("registered pubsub driver: %v", knownNames)
}
func RegisterDriver(d Driver, knownNames ...string) {
	for _, k := range knownNames {
		drivers[strings.ToLower(k)] = d
	}
	log.Info("registered pubsub driver: %v", knownNames)
}
// RegisterDriver registers driver with given names.