Accept None as start and stop parameters for list.index() and tuple.index()

Closes #13340.
diff --git a/Misc/NEWS b/Misc/NEWS
index de3d3f3..720fef3 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #13340: Accept None as start and stop parameters for
+  list.index() and tuple.index().
+
 - Issue #13343: Fix a SystemError when a lambda expression uses a global
   variable in the default value of a keyword-only argument:
   (lambda *, arg=GLOBAL_NAME: None)