my $updater = XML::Rules->new(
	style => 'filter',
	rules => {
		_default => 'raw',
		head => sub {
			my ($tag, $attr) = @_;
			$attr->{_content} = shift(@$heads);
			return $tag => $attr;
		}
	}
);

$updater->filterfile( $big_file_name, $updated_big_file_name);