def METHOD_NAME(message):
    """Check country codes against iso3166 alpha-2 list.
    """
    et, err_list = message
    elements = et.findall('//*[@country]')
    for elem in elements:
        value = elem.attrib['country']
        if value not in ISO3166_CODES_SET():
            err = StyleError()
            err.line = elem.sourceline
            err.message = "Element '%s', attribute country: Invalid country code \"%s\"." % (elem.tag, value)
            err_list.append(err)
    return message