> (define x 2)
> x
2
> (set! x 5)
> x
5
> (define x 10)
> x
10
> (set! x 20)
> x
20
> (f 2)
9
> (f 2)
9
> (f 2)
2
3
9
> set!
[image] set!: bad syntax in: set!
> (f 2)
510
11
121
> (f 2)
5
10
11
121