CitiesEnumProtocol.swift

protocol LocationProtocol {
    //    func address() -> String
}

extension LocationProtocol {
}

enum Cities{}

extension Cities {
    enum Boston{}
    enum Chicago{}
}

extension Cities.Boston {
    enum Streets: String, LocationProtocol {
        case firstStreet = "First Street"
        case secondStreet = "Second Street"
    }
    
    enum Avenues:String, LocationProtocol{
        case firstAvenue = "First Avenue"
        case secondAvenue = "Second Avenue"
    }
}

extension Cities.Chicago {
    enum Streets: String, LocationProtocol {
        case firstStreet = "First Street"
        case secondStreet = "Second Street"
    }
    
    enum Avenues:String, LocationProtocol{
        case firstAvenue = "First Avenue"
        case secondAvenue = "Second Avenue"
    }
}

var a:LocationProtocol = Cities.Boston.Avenues.firstAvenue

var b:LocationProtocol

b = Cities.Boston.Streets.firstStreet

b = Cities.Chicago.Avenues.secondAvenue


// i like to do this:
// print(b.address)
// Bosten City\nFirst Avenue