function doGet()
{
var feed = UrlFetchApp.fetch('http://stackexchange.com/feeds').getContentText();
var document = XmlService.parse(feed);
var root = document.getRootElement();
var atom = XmlService.getNamespace('http://www.w3.org/2005/Atom');
var entries = document.getRootElement().getChildren('entry', atom);
for (var i = 0; i < entries.length; i++)
{
var id = entries[i].getChildText('id', atom);
if(id.substr(0, 14) != 'http://movies.')
entries[i].detach();
}
feed = XmlService.getCompactFormat().setLineSeparator('\n').setEncoding('UTF-8').setIndent(' ').format(document);