;; A ListOfSymbol (LoS) is either
;; -- empty
;; -- (cons Symbol LoS)

#|
;; f: LOS -> ??
(define (f l)
  (cond
    [(empty? l) ... ]
    [(cons?  l) ... (first l) ... (f (rest l) ...) ]))
|#

;; count: LOS -> Number
;; counts the symbols in los
(define (count los)
  (cond
    [(empty? los) 0]
    [(cons?  los) (+ 1 (count (rest los)))]))
                     

;; Examples/Test
(= (count empty) 0)
(= (count (cons 'one empty)) 1)
(= (count (cons 'one (cons 'two empty))) 2)