Hi,

I was checking the `continuation-mark-set->list` example and one of
them seems missing argument on `call-with-continuation-prompt`

This one
```scheme

(define tag (make-continuation-prompt-tag))
(define key (make-continuation-mark-key))
(define key1 (make-continuation-mark-key))
(define key2 (make-continuation-mark-key))

(with-continuation-mark key 'mark1
  (with-continuation-mark key 'mark2
    (call-with-continuation-prompt
      (lambda ()
        (with-continuation-mark key 'mark3
          (continuation-mark-set->list #f key))))))
```
The document says this should return `(mark3 mark2)` though `mark2` is
outside of `(default-continuation-prompt-tag)`, so it should return
`(mark3)`. (and Racket returns it).

To make it return `(mark3 mark2)`, the `call-with-continuation-prompt`
should take the `tag` defined above.

Could you confirm?

Cheers,

--
_/_/
Takashi Kato
E-mail: xxxxxx@gmail.com