def METHOD_NAME(parent, loc, change_freq, lastmod=None):
    """ create and attach url element to argument *parent*
    """
    url_ele = etree.SubElement(parent, NS + "url")
    create_simple_sub_element(url_ele, 'loc', loc)
    if lastmod is not None:
        create_simple_sub_element(url_ele, "lastmod", lastmod)
    create_simple_sub_element(url_ele, "changefreq", change_freq)
    return url_ele