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).

Doc/ref/ref3.tex

@@ -1978,6 +1978,13 @@ Called to implement the built-in functions
 \function{hex()}\bifuncindex{hex}.  Should return a string value.
 \end{methoddesc}
 
+\begin{methoddesc}[numeric object]{__index__}{self}
+Called to implement operator.index().  Also called whenever Python
+needs an integer object (such as in slicing).  Must return an integer
+(int or long).
+\versionadded{2.5}
+\end{methoddesc}
+
 \begin{methoddesc}[numeric object]{__coerce__}{self, other}
 Called to implement ``mixed-mode'' numeric arithmetic.  Should either
 return a 2-tuple containing \var{self} and \var{other} converted to