Custom fetch_feed() function

feed.php

<?php

function cb_fetch_feed( $url ) {
	require_once( ABSPATH . WPINC . '/class-feed.php' );

	$feed = new SimplePie();

	$feed->set_sanitize_class( 'WP_SimplePie_Sanitize_KSES' );
	// We must manually overwrite $feed->sanitize because SimplePie's
	// constructor sets it before we have a chance to set the sanitization class
	$feed->sanitize = new WP_SimplePie_Sanitize_KSES();

	$feed->set_cache_class( 'WP_Feed_Cache' );
	$feed->set_file_class( 'WP_SimplePie_File' );

	$feed->set_feed_url( $url );
	$feed->set_stupidly_fast( true );
	$feed->init();
	$feed->set_output_encoding( get_option( 'blog_charset' ) );
	$feed->handle_content_type();

	if ( $feed->error() )
		return new WP_Error( 'simplepie-error', $feed->error() );

	return $feed;
}