hw-4.rkt

; #1
(define (sequence low high step)
  (let ([next (+ low step)])
    (if (>= high low)
        (cons low (sequence next high step))
        null)))

; #2
(define (string-append-map xs suffix)
  (map (lambda (x)
       (string-append x suffix))
       xs))

; #3
(define (list-nth-mod xs n)
  (cond [(< n 0) (error "list-nth-mod: negative number")]
        [(null? xs) (error "list-nth-mod: empty list")]
        [#t (length xs)]))

; WIP on #3