[plt-scheme] HTDP 28.1.1 help ????

Hi together,
well scheme really is a fine language, but where I can't go further I can't
go further
Looking into exercise of HTDP 28.1.1 I have the following:

(define Graph '(
                (A (B E))
                (B (E F))
                (C (B D))
                (D ())
                (E (C F))
                (F (D G))
                (G ())))

;; find-route : node node graph -> (listof node) or false
;; to create a path from origination to destination in G 
;; if there is no path, the function produces false 
(define (find-route origination destination G) 
  (cond 
    [(symbol=? origination destination) 
     (list destination)] 
    [else (local 
              ((define possible-route 
                    (find-route/list (neighbors origination G)
                                     destination G))) 
            (cond 
              [(boolean? possible-route) false] 
              [else (cons origination possible-route)]))]))

;; find-route/list : (listof node) node graph -> (listof node) or false 
;; to create a path from some node on lo-originations to destination 
;; if there is no path, the function produces false 
(define (find-route/list lo-Os D G) 
  (cond 
    [(empty? lo-Os) false] 
    [else (local ((define possible-route 
                    (find-route (first lo-Os) D G))) 
            (cond 
              [(boolean? possible-route) 
               (find-route/list 
                (rest lo-Os) D G)] 
              [else possible-route]))])) 


;; find-route : node node nodegraph -> (listof node) or false
;; to create a path from origination to destination in G
;; returns false if there is no path otherwise 
;; returns a list of nodes from origination to destination
;;(define (find-route origination destination G)
  ;...
;;)



;; test-call
(find-route 'A 'F Graph)

would be great if you could give me a feedback for a sollution.
take care

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