Argument type list

I want to create a function that receive a list argument and filter
data with IN operator. Example:

CREATE OR REPLACE FUNCTION "public"."ffoo" (list ???) RETURNS VOID AS
$body$
BEGIN
select * from foo where foo_column in list;
END;
$body$
LANGUAGE 'plpgsql' ;

I played with arrays but I got no success...
Is it possible? How proceed?

Thanks,
Gustavo.

PS: Please C.C. to me, I'm not subscribed in list.