How to use the ipyparallel.error.wrap_exception function in ipyparallel

found_ids = [ rec['msg_id'] for rec in records ]
        pending_ids = [ msg_id for msg_id in found_ids if msg_id in self.pending ]
        if len(records) > len(msg_ids):
            try:
                raise RuntimeError("DB appears to be in an inconsistent state."
                    "More matching records were found than should exist")
            except Exception:
                self.log.exception("Failed to resubmit task")
                return finish(error.wrap_exception())
        elif len(records) < len(msg_ids):
            missing = [ m for m in msg_ids if m not in found_ids ]
            try:
                raise KeyError("No such msg(s): %r" % missing)
            except KeyError:
                self.log.exception("Failed to resubmit task")
                return finish(error.wrap_exception())
        elif pending_ids:
            pass
            # no need to raise on resubmit of pending task, now that we
            # resubmit under new ID, but do we want to raise anyway?
            # msg_id = invalid_ids[0]
            # try:
            #     raise ValueError("Task(s) %r appears to be inflight" % )
            # except Exception:
            #     return finish(error.wrap_exception())

        # mapping of original IDs to resubmitted IDs
        resubmitted = {}

        # send the messages
        for rec in records:
            header = rec['header']

statusonly = content.get('status_only', False)
        pending = []
        completed = []
        content = dict(status='ok')
        content['pending'] = pending
        content['completed'] = completed
        buffers = []
        if not statusonly:
            try:
                matches = self.db.find_records(dict(msg_id={'$in':msg_ids}))
                # turn match list into dict, for faster lookup
                records = {}
                for rec in matches:
                    records[rec['msg_id']] = rec
            except Exception:
                content = error.wrap_exception()
                self.log.exception("Failed to get results")
                self.session.send(self.query, "result_reply", content=content,
                                                    parent=msg, ident=client_id)
                return
        else:
            records = {}
        for msg_id in msg_ids:
            if msg_id in self.pending:
                pending.append(msg_id)
            elif msg_id in self.all_completed:
                completed.append(msg_id)
                if not statusonly:
                    c,bufs = self._extract_record(records[msg_id])
                    content[msg_id] = c
                    buffers.extend(bufs)
            elif msg_id in records:

lost = self.pending[engine]
        for msg_id in list(lost.keys()):
            if msg_id not in lost:
                # prevent double-handling of messages
                continue

            raw_msg = lost[msg_id].raw_msg
            idents, msg = self.session.feed_identities(raw_msg, copy=False)
            parent = self.session.unpack(msg[1].bytes)
            idents = [engine, idents[0]]

            # build fake error reply
            try:
                raise error.EngineError("Engine %r died while running task %r"%(engine, msg_id))
            except:
                content = error.wrap_exception()
            # build fake metadata
            md = dict(
                status=u'error',
                engine=engine.decode('ascii'),
                date=util.utcnow(),
            )
            msg = self.session.msg('apply_reply', content, parent=parent, metadata=md)
            raw_reply = list(map(zmq.Message, self.session.serialize(msg, ident=idents)))
            # and dispatch it
            self.dispatch_result(raw_reply)

        # finally scrub completed/failed lists
        self.completed.pop(engine)
        self.failed.pop(engine)

"""Handle messages known to be on an engine when the engine unregisters.

        It is possible that this will fire prematurely - that is, an engine will
        go down after completing a result, and the client will be notified
        that the result failed and later receive the actual result.
        """

        outstanding = self.queues[eid]

        for msg_id in outstanding:
            self.pending.remove(msg_id)
            self.all_completed.add(msg_id)
            try:
                raise error.EngineError("Engine %r died while running task %r" % (eid, msg_id))
            except:
                content = error.wrap_exception()
            # build a fake header:
            header = {}
            header['engine'] = uuid
            header['date'] = util.utcnow()
            rec = dict(result_content=content, result_header=header, result_buffers=[])
            rec['completed'] = util.ensure_timezone(header['date'])
            rec['engine_uuid'] = uuid
            try:
                self.db.update_record(msg_id, rec)
            except Exception:
                self.log.error("DB Error handling stranded msg %r", msg_id, exc_info=True)

"""a task has become unreachable, send a reply with an ImpossibleDependency
        error."""
        if msg_id not in self.queue_map:
            self.log.error("task %r already failed!", msg_id)
            return
        job = self.queue_map.pop(msg_id)
        # lazy-delete from the queue
        job.removed = True
        for mid in job.dependents:
            if mid in self.graph:
                self.graph[mid].remove(msg_id)

        try:
            raise why()
        except:
            content = error.wrap_exception()
        self.log.debug("task %r failing as unreachable with: %s", msg_id, content['ename'])

        self.all_done.add(msg_id)
        self.all_failed.add(msg_id)

        msg = self.session.send(self.client_stream, 'apply_reply', content,
                                                parent=job.header, ident=job.idents)
        self.session.send(self.mon_stream, msg, ident=[b'outtask']+job.idents)

        self.update_graph(msg_id, success=False)

# use the old header, but update msg_id and timestamp
            fresh = msg['header']
            header['msg_id'] = fresh['msg_id']
            header['date'] = fresh['date']
            msg['header'] = header

            self.session.send(self.resubmit, msg, buffers=rec['buffers'])

            resubmitted[rec['msg_id']] = msg_id
            self.pending.add(msg_id)
            msg['buffers'] = rec['buffers']
            try:
                self.db.add_record(msg_id, init_record(msg))
            except Exception:
                self.log.error("db::DB Error updating record: %s", msg_id, exc_info=True)
                return finish(error.wrap_exception())

        finish(dict(status='ok', resubmitted=resubmitted))
        
        # store the new IDs in the Task DB
        for msg_id, resubmit_id in iteritems(resubmitted):
            try:
                self.db.update_record(msg_id, {'resubmitted' : resubmit_id})
            except Exception:
                self.log.error("db::DB Error updating record: %s", msg_id, exc_info=True)

def db_query(self, client_id, msg):
        """Perform a raw query on the task record database."""
        content = msg['content']
        query = extract_dates(content.get('query', {}))
        keys = content.get('keys', None)
        buffers = []
        empty = list()
        try:
            records = self.db.find_records(query, keys)
        except Exception as e:
            content = error.wrap_exception()
            self.log.exception("DB query failed")
        else:
            # extract buffers from reply content:
            if keys is not None:
                buffer_lens = [] if 'buffers' in keys else None
                result_buffer_lens = [] if 'result_buffers' in keys else None
            else:
                buffer_lens = None
                result_buffer_lens = None

            for rec in records:
                # buffers may be None, so double check
                b = rec.pop('buffers', empty) or empty
                if buffer_lens is not None:
                    buffer_lens.append(len(b))
                    buffers.extend(b)