sub gettag {
    my $self = shift;
    ($self -> { THIS }{ DEPTH } ||= 0)++;
    my $tagref = { SUBTAG => [] };
    # ...
    while ( !/<\// ) {
        push @{$tagref -> { SUBTAG }},
          $self -> gettag(); # recursive call
    }
    # ...
    $self -> { THIS }{ DEPTH }--;
    return $tagref;
}