; Use the data definition of List-of-Number for these three steps.
; STEP 1: Write some data examples of List-of-Number.
; STEP 2: Write the template for functions which consume List-of-Number inputs.
; STEP 3: Use the design recipe and the template you just wrote to design the
;         programs described below.

; A List-of-Number is one of
; - empty
; - (cons Number List-of-Number)

; Data Examples:
; WRITE THESE!

; Template:
; WRITE THIS!


; sum-list : List-of-Number -> Number
; Adds the sum of all the numbers in the list.



; 9-exist? : List-of-Number -> Boolean
; Reports true when the number 9 exists in the list, and false otherwise



; add-toall : List-of-Number -> List-of-Number
; Consume a list of numbers and produce a new list with 5 added to
; each number in the list
; Examples:
(equal? (add-toall empty) empty)
(equal? (add-toall (cons 2 (cons 3 empty)))
        (cons 7 (cons 8 empty)))