1 files changed, 1 insertions, 0 deletions
diff --git a/mdpoly/abc.py b/mdpoly/abc.py
index 657adf7..882634f 100644
--- a/mdpoly/abc.py
+++ b/mdpoly/abc.py
@@ -296,6 +296,7 @@ class Leaf(Expr):
     def left(self):
         """ Overloads left child with function that does nothing. (Leaves do
         not have children). """
+        return Nothing()
 
     @left.setter
     def left(self, left: Self) -> None: