This is a very simple demonstration of Golang library coding style which prevents the caller from using unnamed struct initialization. Doing this ensures that new fields can safely be added to the struct without breaking backwards compatibility.
Use go run main.go to see some output.
I've tried exploring various types, interfaces, fmt.Format and more, to try
to automatically hide the filtering field from fmt.Printf with %#v but to
no avail. I ended up going for a very short name which idiomatically conveys
"unused" to hint at what's going on; could change the type away from
struct{} to int to shorten the %#v output even more.