#!/usr/bin/perl

use strict;
use XML::LibXML;

my $string = qq~<?xml version="1.0"?>
<ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2013-08-01">
  <Items>
    <Item>
      <ASIN>B01KI4JSQY</ASIN>
    </Item>
  </Items>
</ItemLookupResponse>
~;

my $parser = XML::LibXML->new->load_xml(string => $string, {no_blanks => 1});
my $xml = XML::LibXML::XPathContext->new($parser);
$xml->registerNs('x', 'http://webservices.amazon.com/AWSECommerceService/2013-08-01');

# Parse items
foreach my $item ($xml->findnodes('/x:ItemLookupResponse/x:Items/x:Item', $parser)){
        print $item->firstChild->nodeName, "\n";
        print $item->firstChild->toString, "\n";
        print $item->findvalue('ASIN'), "\n";
        print $item->findvalue('./ASIN'), "\n";
        print $item->findvalue('./ASIN', $item), "\n";
}

##</code><code>##

ASIN
<ASIN>B01KI4JSQY</ASIN>
B01KI4JSQY
B01KI4JSQY
B01KI4JSQY

##</code><code>##

ASIN
<ASIN>B01KI4JSQY</ASIN>