wordpress 3.7.1 breaking site

below code is not working. it was working in 3.7 and prior version. particular this line.

$maxitems = $rss->get_item_quantity(30);

<p class="sidehead" id="hackn">Hacker News 30</p>
<?php include_once(ABSPATH.WPINC.'/feed.php');
$rss = fetch_feed('https://news.ycombinator.com/rss');
$maxitems = $rss->get_item_quantity(30);
$rss_items = $rss->get_items(0, $maxitems);
?>
<ul>
<?php if ($maxitems == 0) echo '<li>No items.</li>';
else
// Loop through each feed item and display each item as a hyperlink.
foreach ( $rss_items as $item ) : ?>
<li class="hackernews">
<a href='<?php echo $item->get_permalink(); ?>'>
<?php
$posttit = $item->get_title();
if(!empty($posttit)) {
  echo $posttit;
} else {
  echo "Undefined post title";
}
?></a>
</li>
<?php endforeach; ?>
</ul>