Step6.swift

struct ViewModel {
  var person: Person
  var nameAndAddress: String {
   return "\(person.firstName)\(person.lastName), \(person.address)"
  }

  init() {
    person = Person(firstName: "John", 
                    lastName: "Appleseed", 
                    address: "1 Infinite Loop, Cupertino, CA")
  }
}