From a3794f2701eb54393b44d13da11680ec5314b8b8 Mon Sep 17 00:00:00 2001
From: aksagrimada <1955605+aksagrimada@users.noreply.github.com>
Date: Tue, 6 Aug 2019 07:16:00 +0100
Subject: [PATCH] Resolve invalid escape sequence

When run not as a decorator dynamodb2 displays an invalid escape sequence error
/moto/dynamodb2/responses.py:603: DeprecationWarning: invalid escape sequence \s
  '\s*([=\+-])\s*', '\\1', update_expression)
---
 moto/dynamodb2/responses.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/moto/dynamodb2/responses.py b/moto/dynamodb2/responses.py
index d34b176a7..86ca9a362 100644
--- a/moto/dynamodb2/responses.py
+++ b/moto/dynamodb2/responses.py
@@ -600,7 +600,7 @@ class DynamoHandler(BaseResponse):
         # E.g. `a = b + c` -> `a=b+c`
         if update_expression:
             update_expression = re.sub(
-                '\s*([=\+-])\s*', '\\1', update_expression)
+                r'\s*([=\+-])\s*', '\\1', update_expression)
 
         try:
             item = self.dynamodb_backend.update_item(