Fix Tuple modification example

ecmendenhall · web-flow · commit 6b4321445cd6 · 2017-09-14T21:01:20.000-04:00
diff --git a/python/lesson3/tutorial.md b/python/lesson3/tutorial.md
@@ -168,10 +168,10 @@ tuple, you can always *cast* it as a list:
     my_tuple = (1, 2, 3)
 
     my_list = list(my_tuple)
-    my_list[3] = 99
+    my_list[2] = 99
 
     my_list
-    [1, 2, 3, 99]
+    [1, 2, 99]
 
     my_tuple
     (1, 2, 3)
