import urllib2

USER_AGENT = 'Calcium/1.0 +http://feedtree.net/ (FeedTree + CoralCDN)'

def urlfetch(url, length=-1):
    req = urllib2.Request(url)
    req.add_header('User-Agent', USER_AGENT)
    opener = urllib2.build_opener()
    return opener.open(req).read(length)