From 6f5597117708748a219fbe8d89d242b3ed35b625 Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Fri, 8 Oct 2021 13:06:10 -0700
Subject: [PATCH] Newderiv (#5585)

* updated derivative engine

* some edit

* further improvements in derivative code

* more deriv code edits and re::to_str update

* optimized mk_deriv_accept

* fixed PR comments

* small syntax fix

* updated some simplifications

* bugfix:forgot to_re before reverse

* fixed PR comments

* more PR comment fixes

* more PR comment fixes

* forgot to delete

* deleting unused definition

* fixes

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

Co-authored-by: Margus Veanes <margus@microsoft.com>