code: private CompletableFuture<QueryResponse> queryLinearizable(QueryEntry entry) {
      return sequenceAndApply(entry)
        .thenCompose(response -> appender.appendEntries()
          .thenApply(index -> response)
          .exceptionally(error -> QueryResponse.builder()
            .withStatus(Response.Status.ERROR)
            .withError(CopycatError.Type.QUERY_ERROR)
            .build()));
    }
docs: Executes a linearizable query.
  <p>
  Linearizable queries are first sequenced with commands and then applied to the state machine. Once
  applied, we verify the node's leadership prior to responding successfully to the query.