From 7e39635b0978cde96584eb2ac10d3c5a9a9b9b52 Mon Sep 17 00:00:00 2001
From: Sei Lisa <sei-lisa@email.fake>
Date: Sat, 21 Oct 2017 20:38:54 +0200
Subject: [PATCH] Transform !(x != y) into x == y.

Can happen with lists.
---
 lslopt/lslfoldconst.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lslopt/lslfoldconst.py b/lslopt/lslfoldconst.py
index 1c10f66..7d086f0 100644
--- a/lslopt/lslfoldconst.py
+++ b/lslopt/lslfoldconst.py
@@ -640,6 +640,12 @@ class foldconst(object):
                     subexpr['ch'] = [subexpr['ch'][b], subexpr['ch'][a]]
                     parent[index] = subexpr
                     return
+            if snt == '!=':
+                subexpr['nt'] = '=='
+                parent[index] = subexpr
+                self.FoldTree(parent, index)
+                return
+
             return
 
         if nt == '~':