Reports unused function parameters.
func main() {
 printAll(
  42,
  "bird",
 )
}

func printAll(
 i int,
 s string,
) {
 fmt.Println(i)
}

We call the printAll function passing 42 and bird as arguments. The printAll function accepts two parameters int and string but uses only the first of them. Therefore, the s string is grayed out.