my $struct = $section->simplify( forcearray => 1 );

##</code><code>##

sub uml_class
{
    my ( $twig, $section ) = @_;

    print "data for class:\n";
    print "   name = ", $section->att( 'name' ), "\n";
    print "   xmi.id = ", $section->att( 'xmi.id' ), "\n";

    my $subTwig = XML::Twig->new( twig_roots => {
                                      'UML:Attribute' => \&uml_attr } );
    # $subTwig->parse( $xml ); # original code (typo)
    $subTwig->parse( $section->sprint() );
}