Use "impl-detail" directive where applicable.
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index e1b0ada..6481894 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -663,13 +663,13 @@
raised. Otherwise, the list of filled slots is used as the argument list for
the call.
-.. note::
+.. impl-detail::
- An implementation may provide built-in functions whose positional parameters do
- not have names, even if they are 'named' for the purpose of documentation, and
- which therefore cannot be supplied by keyword. In CPython, this is the case for
- functions implemented in C that use :cfunc:`PyArg_ParseTuple` to parse their
- arguments.
+ An implementation may provide built-in functions whose positional parameters
+ do not have names, even if they are 'named' for the purpose of documentation,
+ and which therefore cannot be supplied by keyword. In CPython, this is the
+ case for functions implemented in C that use :cfunc:`PyArg_ParseTuple` to
+ parse their arguments.
If there are more positional arguments than there are formal parameter slots, a
:exc:`TypeError` exception is raised, unless a formal parameter using the syntax