class Person1 { constructor ( public firstName , public lastName , public age , private _ssn ? ) { } get ssn ( ) : string { return this . _ssn ; } set ssn ( value ) { this . _ssn = value ; } } let person = new Person1 ( "John" , "Smith" , 29 ) ; person . ssn = "456-70-1234" ; console . log ( "Last name: " + person . lastName + " SSN: " + person . ssn ) ;