diff --git a/python.html.markdown b/python.html.markdown
index 52ad6308..bd6090c7 100644
--- a/python.html.markdown
+++ b/python.html.markdown
@@ -706,6 +706,7 @@ def double_numbers(iterable):
     double_arr = []
     for i in iterable:
         double_arr.append(i + i)
+    return double_arr
 
 
 # Running the following would mean we'll double all values first and return all