Methods and computed variables

Let's imagine that it is important for us to know whether a person's title relates to a professional qualification that the person holds. Let's add a method to our enum to provide that information:

enum Title: String { 
    case mr = "Mr" 
    case mrs = "Mrs" 
    case mister = "Master" 
    case miss = "Miss" 
    case dr = "Dr" 
    case prof = "Prof" 
    case other // Inferred as "other" 

    func isProfessional() -> Bool { 
        return self == Title.dr || self == Title.prof 
    }
}

For the list of titles that we have defined, Dr and Prof relate to professional qualifications, so we have our method return true if self (the instance of the enum type this method is called on) is equal to the dr case, or equal to the prof case.

In defining this method, we used ||, which is the OR logical operator. Using this operator returns a true Bool value if the expression...