KiraBen

(define (lst-without-first-occurrence-of lst element)
  (cond
    [(empty? lst) empty]
    [(= (first lst) element) (rest lst) ]
    [else (cons (first lst) (lst-without-first-occurrence-of (rest lst) element))]))

(define ( len lst)
  (cond
    [(empty? lst) 0]
    [else (+ 1 (len (rest lst)))]))