Bug #1697820: document that the old slice protocol is still used by builtin types.
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 3e55372..030d1d9 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1819,6 +1819,9 @@
.. deprecated:: 2.0
Support slice objects as parameters to the :meth:`__getitem__` method.
+ (However, built-in types in CPython currently still implement
+ :meth:`__getslice__`. Therefore, you have to override it in derived
+ classes when implementing slicing.)
Called to implement evaluation of ``self[i:j]``. The returned object should be
of the same type as *self*. Note that missing *i* or *j* in the slice