sub make_printer {
	my $hdr = shift;
	my $count;
	return bless sub {
		my $item = shift || do {
			print "\n" if $count;
			return;
		};
		print( ( $count ? "," : "$hdr:") , " ", $item );
		++$count;
	}, 'PRINTER';
	sub PRINTER::DESTROY { shift->() }
}