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)=@_;
	my $xml_ex = '';
	foreach my $tag (keys %$rec) {
		$xml_ex = "<$tag>" . $rec->{$tag} . "\n";
	}
	return $xml_ex;
$a$ language plperlu;

Thanks,
Sean