How to use the execnet.gateway_base.DumpError function in execnet

def _save(self, obj):
        tp = type(obj)
        try:
            dispatch = self._dispatch[tp]
        except KeyError:
            methodname = "save_" + tp.__name__
            meth = getattr(self.__class__, methodname, None)
            if meth is None:
                raise DumpError("can't serialize {}".format(tp))
            dispatch = self._dispatch[tp] = meth
        dispatch(self, obj)

def _write_int4(self, i, error="int must be less than %i" % (FOUR_BYTE_INT_MAX,)):
        if i > FOUR_BYTE_INT_MAX:
            raise DumpError(error)
        self._write(struct.pack("!i", i))

def _write_unicode_string(self, s):
        try:
            as_bytes = s.encode("utf-8")
        except UnicodeEncodeError:
            raise DumpError("strings must be utf-8 encodable")
        self._write_byte_sequence(as_bytes)

def serialize_warning_message(warning_message):
    if isinstance(warning_message.message, Warning):
        message_module = type(warning_message.message).__module__
        message_class_name = type(warning_message.message).__name__
        message_str = str(warning_message.message)
        # check now if we can serialize the warning arguments (#349)
        # if not, we will just use the exception message on the master node
        try:
            dumps(warning_message.message.args)
        except DumpError:
            message_args = None
        else:
            message_args = warning_message.message.args
    else:
        message_str = warning_message.message
        message_module = None
        message_class_name = None
        message_args = None
    if warning_message.category:
        category_module = warning_message.category.__module__
        category_class_name = warning_message.category.__name__
    else:
        category_module = None
        category_class_name = None

    result = {