discovery.go
func Proto(service, name string) (string, error) {
	template := fmt.Sprintf(templateVar, service, name)
	return getVar(fmt.Sprintf(template, "PROTO"))
}
func Proto(service, name string) (string, error) {
	template := fmt.Sprintf(templateVar, service, name)
	return getVar(fmt.Sprintf(template, "PROTO"))
}
// Proto finds the specified protocol for a service based off of the service's name and which
// interface you are accessing. Values are found in environment variables fitting the scheme:
// SERVICE_{SERVICE NAME}_{INTERFACE NAME}_PROTO.