#
A list of the squares
^{
}

The procedure square-list takes a list of numbers as argument and returns a list of the squares of those numbers.

```
(square-list (list 1 2 3 4))
```*(1 4 9 16)*

Here are two different definitions of square-list. Complete both of them by filling in the missing expressions:

```
(define (square-list items)
(if (null? items)
nil
(cons <??> <??>)))
(define (square-list2 items)
(map <??> <??>))
```

```
(define test-list (list 3 5 7 8 21 4))
(check-equal? (square-list (list 1 2 3 4)) (list 1 4 9 16))
(check-equal? (square-list test-list) (square-list2 test-list))
```