diff --git a/demo_code.py b/demo_code.py
index db32dd49d..0cc8c159b 100644
--- a/demo_code.py
+++ b/demo_code.py
@@ -16,7 +16,7 @@ def __init__(self):
         self.limits = (1, 10)
 
     def get_number(self, min_max):
-        raise NotImplemented
+        raise NotImplementedError
 
     def smethod():
         """static method-to-be"""