main.go

package main
import(
    "painter"
    "fmt"
)
func main(){
	res := painter.Repaint(painter.Deferred)
	fmt.Println(res)
}

painter.go

package painter
type RepaintMode bool

const (
	Immediate RepaintMode = true
	Deferred              = false
)

func Repaint(mode RepaintMode) string {
	if mode == Immediate {
		return "Immediate"
	} else {
		return "Deferred"
	}
        panic("unreachable code")
}