sub process_article {
	my $article = get_article_from_db($article_id);
	my $contents = process_article($article->{contents});
	# now I need to access $article->{contents}, but the modified version from process_article
}

sub process_article {
	my $article_contents = $_[0];
	# do some stuff to $article_contents here
	return $article_contents;
}