1 ;; Exercise 2.27.  Modify your reverse procedure of exercise 2.18 to produce a deep-reverse procedure that takes a list as argument and returns as its value the list with its elements reversed and with all sublists deep-reversed as well. For example,
2 
3 (define (deep-reverse tree)
4   (cond ((null? tree) '())
5 	((not (pair? tree)) tree)
6 	(else (append
7 	       (deep-reverse (cdr tree))
8 	       (list (deep-reverse (car tree)))))))
9 
10 (define (test-case actual expected)
11   (newline)
12   (display "Actual: ")
13   (display actual)
14   (newline)
15   (display "Expected: ")
16   (display expected)
17   (newline))
18 
19 (define x (list (list 1 2) (list 3 4)))
20 
21 (test-case (reverse x) '((3 4) (1 2)))
22 
23 (test-case (deep-reverse x) '((4 3) (2 1)))