Person {
  var firstname: String
  var middlename: String? //we created the optional with the ?
  var lastname: String

  func fullName() -> () {
     print("Your fullname is \(firstname) \(middlename!) \(lastname)")
  }
}

let me = Person(firstname: "Abel", middlename: "Agoi", lastname: "Adeyemi")

me.fullName() //will return "Your fullname is Abel Agoi Adeyemi"