netrc python http auth

def download(url, filepath):
    print "downloading %s to %s" % (url, filepath)
    parts = urlparse(url)
    login, account, password = netrc.netrc().authenticators(parts.netloc)
    request = urllib2.Request(url)
    creds = base64.encodestring('%s:%s' % (login, password)).strip()
    request.add_header("Authorization", "Basic %s" % creds)
    result = urllib2.urlopen(request)
    assert result.getcode() == 200
    f = open(filepath, 'wb')
    f.write(result.read());
    f.close()