Function with record type as argument

In a followup to an earlier question from today from another person, is
it possible to create and use a function that takes as input a generic
"record"? Specifically, how would I use a function like:

create or replace function perl_columns(record) returns text as $a$
my ($rec)=(at)_;
my $xml_ex = '';
foreach my $tag (keys %$rec) {
$xml_ex = "<$tag>" . $rec->{$tag} . "</$tag>\n";
}
return $xml_ex;
$a$ language plperlu;

Thanks,
Sean