feature_one 2 R 4 V feature_two 5 S ##
##


#!/usr/bin/perl

# use module

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

my $file = shift;

my $twig= new XML::Twig(
    twig_handlers => { residue => \&residue }
);

$twig->parsefile($file);

sub residue
{
    my ($twig, $res) = @_;

    my $res_idx = $res->first_child('residue_index')->text;
    my $res_name = $res->first_child('residue_name')->text;

    print "$res_idx $res_name\n";
      
}