For a given URL return the netloc with any www. striped.

def netloc_no_www(url):
    """
    For a given URL return the netloc with any www. striped.
    """
    ext = tldextract.extract(url)
    if ext.subdomain and ext.subdomain != 'www':
        return '%s.%s.%s' % (ext.subdomain, ext.domain, ext.tld) 
    else:
        return '%s.%s' % (ext.domain, ext.tld)