https://github.com/thom311/libnl/blob/libnl3_2_25/lib/handlers.c#L78.

def nl_error_handler_verbose(_, err, arg):
    """https://github.com/thom311/libnl/blob/libnl3_2_25/lib/handlers.c#L78."""
    ofd = arg or _LOGGER.debug
    ofd('-- Error received: ' + strerror(-err.error))
    ofd('-- Original message: ' + print_header_content(err.msg))
    return -nl_syserr2nlerr(err.error)