Exercise 2.17. Define a procedure last-pair that returns the list that contains only the last element of a given (nonempty) list:
(last-pair (list 23 72 149 34))
(34)
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| (define (last-pair list1) | |
| (if | |
| (null? list1) | |
| '() | |
| (if | |
| (null? (cdr list1)) | |
| (car list1) | |
| (last-pair (cdr list1))))) | |
| (last-pair (list 1 2 3 4 5)) | |
| (last-pair (list 1)) | |
| (last-pair ()) | |
| (last-pair '()) | |