my $res = $o->pm_get( node_id => 180684, id => 505536, flattree => 1 );

my $data = XMLin( $res->content, ForceArray => 0 );

my %nodes;

foreach my $node ( @{ $data->{node} } ) {

    my $nid = $node->{node_id};

    # register this node so children can find it
    $nodes{ $nid } = $node;

    if ( my $pid = $node->{parent_node} ) {

        # tell the parent about this child
        $nodes{$pid}{kids}{$nid} = $node;

        # make the reference to the parent "hard" and not "soft"
        $node->{parent} = $nodes{$pid};

    }

}