import urllib2
from lxml import etree

webPageUrl = "http://www.osmonov.com"
try:
    opener = urllib2.build_opener()
    response = opener.open(webPageUrl)
    if response.headers.__getitem__('Content-Type').startswith('text/html'):
        html_element = etree.HTML( response.read() )
        link_elements =html_element.findall('.//link[@rel="alternate"]')
        if link_elements.__len__() > 0:
            # so we can have several link tags, i use just the first
            feedUrl = link_elements.__getitem__(0).get('href')

except urllib2.URLError:
    # commander! do something violent