document 'y(#)' format codes for Py_BuildValue
diff --git a/Doc/c-api/arg.rst b/Doc/c-api/arg.rst
index c3d051a..94f62f1 100644
--- a/Doc/c-api/arg.rst
+++ b/Doc/c-api/arg.rst
@@ -424,6 +424,14 @@
Convert a C string and its length to a Python object. If the C string pointer
is *NULL*, the length is ignored and ``None`` is returned.
+ ``y`` (bytes) [char \*, int]
+ This converts a C string to a Python :func:`bytes` object. If the C
+ string pointer is *NULL*, ``None`` is returned.
+
+ ``y#`` (bytes) [char \*, int]
+ This converts a C string and its lengths to a Python object. If the C
+ string pointer is *NULL*, ``None`` is returned.
+
``z`` (string or ``None``) [char \*]
Same as ``s``.