my $_consume = sub {
    print $indent x $_[2], substr $_[0], 0, $_[1], '';
  }

  sub pp {
    return unless @_;
    my($str) = @_;
    my($length, $first) = f1($str);

    if (!defined $first) {
      $_consume->($str, $length, $depth);
    } elsif ($first eq CONST1) {