#!/usr/bin/perl

{
    package XML::Simple::Ordered;    # subclass overriding new_hashref method
    
    use base qw(XML::Simple);
    use Tie::IxHash;
    
    sub new_hashref {
        my $self = shift;
        my %hash;
        tie %hash, 'Tie::IxHash', @_;
        return \%hash;
    }

}

package main;

my $simple = XML::Simple::Ordered->new();
my $data = $simple->XMLin($file);

##</code><code>##

sub collapse {
  my $self = shift;

  # Start with the hash of attributes
  
  my $attr  = shift;
  $attr = $self->new_hashref() unless %$attr;    # <-- add this line