Mention Py_RETURN_NONE when introducing the idiom of how to have a function
return Py_None.
diff --git a/Doc/ext/extending.tex b/Doc/ext/extending.tex
index 57adc15..c3d3ab0 100644
--- a/Doc/ext/extending.tex
+++ b/Doc/ext/extending.tex
@@ -290,7 +290,8 @@
If you have a C function that returns no useful argument (a function
returning \ctype{void}), the corresponding Python function must return
-\code{None}. You need this idiom to do so:
+\code{None}. You need this idiom to do so (which is implemented by the
+\csimplemacro{Py_RETURN_NONE} macro):
\begin{verbatim}
Py_INCREF(Py_None);