sub print_struct {
    my ($ref,$depth) = @_;
    $depth++;                                   # Tiefe für Tabs
    foreach my $entry (sort keys %{$ref}) {
        if( (ref $ref->{$entry}) eq 'HASH') {
            print "\t" x $depth, $entry, "\=\>\n";
            print_struct($ref->{$entry}, $depth);
        } else {
            print "\t" x ($depth), $entry, "\n";
        }
    }
}