def nl_valid_handler_debug(msg, arg):
    """https://github.com/thom311/libnl/blob/libnl3_2_25/lib/handlers.c#L92."""
    ofd = arg or _LOGGER.debug
    ofd('-- Debug: Unhandled Valid message: ' + print_header_content(nlmsg_hdr(msg)))
    return NL_OK
https://github.com/thom311/libnl/blob/libnl3_2_25/lib/handlers.c#L92.