Script-Fu: gimp-image-get-filename does not return string?

[bliss]

I'm probably doing something stupid?
(Scheme and Script-Fu first timer)

Does

Code:

(gimp-image-get-filename 1)

not return a string?
Script-Fu Procedure Browser says so at least.

Code:

> (string-length (gimp-image-get-filename 1))
Error: string-length: argument 1 must be: string

Thank you for your time and effort kind stranger!

---

I had to do:

Code:

(string-length (car(gimp-image-get-filename 1)))

Where the (car x) is the important part.

Seems to be a Lisp thing where everything returns a  pair or a list and car selects the first element of a pair/list.