It looks like @landscape_lgl contains a value set_paper(5), and it's unlikely you have
made a method with that name in the package.
So Perl will complain. The "explaination" given by
diagnostics is confusing - ignore it.
Indeed. And that's the problem. You are trying to call a
method named set_paper(5), and that method doesn't
exist. It's not going to call set_paper
with argument 5.