Issue #19795: Mark up None as literal text.
diff --git a/Doc/library/optparse.rst b/Doc/library/optparse.rst
index 5466462..4af75a1 100644
--- a/Doc/library/optparse.rst
+++ b/Doc/library/optparse.rst
@@ -2028,12 +2028,12 @@
values.ensure_value(attr, value)
- If the ``attr`` attribute of ``values`` doesn't exist or is None, then
+ If the ``attr`` attribute of ``values`` doesn't exist or is ``None``, then
ensure_value() first sets it to ``value``, and then returns 'value. This is
very handy for actions like ``"extend"``, ``"append"``, and ``"count"``, all
of which accumulate data in a variable and expect that variable to be of a
certain type (a list for the first two, an integer for the latter). Using
:meth:`ensure_value` means that scripts using your action don't have to worry
about setting a default value for the option destinations in question; they
- can just leave the default as None and :meth:`ensure_value` will take care of
+ can just leave the default as ``None`` and :meth:`ensure_value` will take care of
getting it right when it's needed.