From b53de690d57bb04dc747b791371210a19de91c8d Mon Sep 17 00:00:00 2001
From: Bertrand Benjamin <benjamin.bertrand@opytex.org>
Date: Mon, 15 Jul 2019 17:27:38 +0200
Subject: [PATCH] Fix: Issue with typing null monomial

---
 mapytex/calculus/core/typing/multiply.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mapytex/calculus/core/typing/multiply.py b/mapytex/calculus/core/typing/multiply.py
index 9042f77..fd0d074 100644
--- a/mapytex/calculus/core/typing/multiply.py
+++ b/mapytex/calculus/core/typing/multiply.py
@@ -34,6 +34,17 @@ def multiply_filter(left, right):
     :param right: MO
     :returns: MO if it is a special case, nothing other wise
     """
+    try:
+        if left == 0:
+            return left
+    except TypeError:
+        pass
+    try:
+        if right == 0:
+            return right
+    except TypeError:
+        pass
+
     try:
         if left == 1:
             return right