Checking in the code for PEP 357.
This was mostly written by Travis Oliphant.
I've inspected it all; Neal Norwitz and MvL have also looked at it
(in an earlier incarnation).
diff --git a/Doc/api/abstract.tex b/Doc/api/abstract.tex
index c543563..320275c 100644
--- a/Doc/api/abstract.tex
+++ b/Doc/api/abstract.tex
@@ -346,6 +346,7 @@
   either the sequence and mapping protocols, the sequence length is
   returned.  On error, \code{-1} is returned.  This is the equivalent
   to the Python expression \samp{len(\var{o})}.\bifuncindex{len}
+  \versionadded{2.5}
 \end{cfuncdesc}
 
 
@@ -689,6 +690,10 @@
   \samp{float(\var{o})}.\bifuncindex{float}
 \end{cfuncdesc}
 
+\begin{cfuncdesc}{Py_ssize_t}{PyNumber_Index}{PyObject *o}
+  Returns the \var{o} converted to a Py_ssize_t integer on success, or
+  -1 with an exception raised on failure.
+\end{cfuncdesc}
 
 \section{Sequence Protocol \label{sequence}}