diff --git a/src/sample/simple.py b/src/sample/simple.py
index c929f885..725b9651 100644
--- a/src/sample/simple.py
+++ b/src/sample/simple.py
@@ -1,2 +1,6 @@
 def add_one(number):
-    return number + 1
+    if number is None:
+        return None
+    return number + 2
+
+