var costume: String? = "Werewolf"
println(costume) // Optional("Werewolf")

costume = costume + " dressed as Michael J Fox" // Compiler Error

if let something = costume {
// The value is not nil, use it with confidence
something = something + " dressed as Michael J Fox"
println(something) // "Werewolf dressed as Michael J Fox"
} else {
// The value is nil
}