sub parent {
    my ( $self, @parent ) = @_;
    $self->{parent} = $parent[0] if scalar(@parent);
    return $self->{parent};
}
# oder
sub parent2 {
    my $self = shift @_;
    my ($parent) = @_;
    if( scalar @_ ) {
      $self->{parent2} = $parent;
    }
    return $self->{parent2};
}