How to use the pymemcache.exceptions.MemcacheClientError function in pymemcache

def test_error(self):
        with self.server_span:
            with self.assertRaises(MemcacheClientError):
                self.context.memcache.cas("key", b"value", b"whatever")

        server_span_observer = self.baseplate_observer.get_only_child()
        span_observer = server_span_observer.get_only_child()
        self.assertEqual(span_observer.span.name, "memcache.cas")
        self.assertTrue(span_observer.on_start_called)
        self.assertTrue(span_observer.on_finish_called)
        self.assertIsNotNone(span_observer.on_finish_exc_info)

def test_set_client_error(self):
        client = self.make_client([b'CLIENT_ERROR some message\r\n'])

        def _set():
            client.set('key', 'value', noreply=False)

        pytest.raises(MemcacheClientError, _set)

        spans = self.check_spans(1, ['set'], ['set key'])
        self.assertEqual(spans[0].error, 1)

def _raise_errors(self, line, name):
        if line.startswith(b'ERROR'):
            raise MemcacheUnknownCommandError(name)

        if line.startswith(b'CLIENT_ERROR'):
            error = line[line.find(b' ') + 1:]
            raise MemcacheClientError(error)

        if line.startswith(b'SERVER_ERROR'):
            error = line[line.find(b' ') + 1:]
            raise MemcacheServerError(error)

)

            # try to set relevant tags, catch any exceptions so we don't mess
            # with the application
            try:
                span.set_tags(p.tags)
                vals = _get_query_string(args)
                query = '{}{}{}'.format(method_name, ' ' if vals else '', vals)
                span.set_tag(memcachedx.QUERY, query)
            except Exception:
                log.debug('Error setting relevant pymemcache tags')

            try:
                return method(*args, **kwargs)
            except (
                MemcacheClientError,
                MemcacheServerError,
                MemcacheUnknownCommandError,
                MemcacheUnknownError,
                MemcacheIllegalInputError,
            ):
                (typ, val, tb) = sys.exc_info()
                span.set_exc_info(typ, val, tb)
                reraise(typ, val, tb)