use strict;
use warnings;
use XML::Simple;
use Data::Dumper;

my @forms = qw(first second third);
my $tree;
my $vxml;

my $filename = 'vxml_tree.xml';

$vxml->{forms}->{$_} = ['dummy', { more_dummy => 'more' }] for (@forms);
$tree->{system_1} = $vxml;

print Dumper $tree;

my $xs = new XML::Simple();
my $xml = $xs->XMLout($tree);
open my $fh, '>', $filename or die $!;
print $fh $xml;
close $fh;

$tree = $xs->XMLin($filename);

print Dumper $tree;