sub list {
  # And again, $tab is a number.
  # $list is an array ref of values.
  # $opt is the few available options for lists.
  my ($tab,$list,$opt) = @_;

  my @attributes;
  push @attributes, qq(id="$opt->{id}")       if $opt->{id};
  push @attributes, qq(class="$opt->{class}") if $opt->{class};
  push @attributes, qq(style="$opt->{style}") if $opt->{style};

  my $format = @attributes > 0 ? ' '.join(' ',@attributes) : '';
  my $tag = 'ul'.$format;

  line($tab,qq(<$tag>));
  line($tab + 1,qq(<li>$_</li>)) for @{$list};
  line($tab,q(</ul>));
}