package addressbook class Contact( val name : String, val emails : List, val addresses : List, val phonenums : List ) class EmailAddress( val user : String, val host : String ) class PostalAddress( val streetAddress : String, val city : String, val zip : String, val state : USState?, val country : Country ) { assert {(state == null) xor (country == Countries["US"]) } } class PhoneNumber( val country : Country, val areaCode : Int, val number : Long ) object Countries { fun get(id : CountryID) : Country = countryTable[id] private var table : Map? = null private val countryTable : Map get() { if (table == null) { table = HashMap() for (line in TextFile("countries.txt").lines(stripWhiteSpace = true)) { table[line] = Country(line) } } return table } } class Country(val name : String)