-> ; every respons in column 0 is one test
-> (define cell () ; a definition, not a test, because response is left out
     (let 
       ((x '()))
       (cons
         (lambda (y) (set x y))
         (lambda () x))))
-> (val v (cell))     ; more definitions...
-> (val put (car v))
-> (val get (cdr v))
-> (put 5) ; this is the first test (response is shown)
5
-> (get) ; this is the second test
5
-> ; this definition supports the third test
-> (define reverse (l) (foldl cons '() l))
-> (reverse '(1 2 3)) ; the final test
(3 2 1)