Understanding variable.(Type) in go [duplicate]

I don't really understand how this code works, specifically e.(Exit), could someone explain?

type Exit struct{ Code int }
func handleExit() {
    if e := recover(); e != nil {
        if exit, ok := e.(Exit); ok == true {
            os.Exit(exit.Code)
        }
        panic(e)
     }
}

func main() {
    defer handleExit()
    panic(Exit{1})
}