bpo-14050: Note that not all data can be sorted (GH-15381) (GH-15395)
(cherry picked from commit 4109263a7edce11194e301138cf66fa2d07f7ce4)
Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
diff --git a/Doc/tutorial/datastructures.rst b/Doc/tutorial/datastructures.rst
index 01e437b..a0d5627 100644
--- a/Doc/tutorial/datastructures.rst
+++ b/Doc/tutorial/datastructures.rst
@@ -125,6 +125,13 @@
``None``. [1]_ This is a design principle for all mutable data structures in
Python.
+Another thing you might notice is that not all data can be sorted or
+compared. For instance, ``[None, 'hello', 10]`` doesn't sort because
+integers can't be compared to strings and *None* can't be compared to
+other types. Also, there are some types that don't have a defined
+ordering relation. For example, ``3+4j < 5+7j`` isn't a valid
+comparison.
+
.. _tut-lists-as-stacks: