[Orgmode] preparation-function syntax for publishing

[Julien Barnier]

Dear org users,

I'm trying to use the :preparation-function argument for project
publishing. What I'd like to achieve i s to load a file in order to
define some styling elements for the export process, something such 
as :

(load "org-style")

I tried several different syntaxes, such as :

:preparation-function (load "org-style")

But I didn't manage to achieve it, whichever syntax I try I get an
invalid function error.

Do you know if there is a way to declare such a thing ?

Thanks a lot in advance for any help.

-- 
Julien