Guided Practice 4.1

Consider the following data definition:

;; A ListOfStrings (LOS) is one of
;; -- empty
;; -- (cons String LOS)

Which of the following expressions have values that are LOS's?

1. (cons "abc" empty)
2. (cons "bcd")
3. (cons "cde" (cons "ef" empty))
4. (cons "3" (cons "4" empty))
5. (cons 3 (cons 4 empty))

[ANSWER]