Document the new list.extend() method. Interesting enough, the
canonical definition of extend() is very similar to append() except
that the former doesn't list-ify the argument!
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index ff31c5e..57c43d5 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -452,6 +452,8 @@
{same as \code{\var{s}[\var{i}:\var{j}] = []}}{}
\lineiii{\var{s}.append(\var{x})}
{same as \code{\var{s}[len(\var{s}):len(\var{s})] = [\var{x}]}}{}
+ \lineiii{\var{s}.extend(\var{x})}
+ {same as \code{\var{s}[len(\var{s}):len(\var{s})] = \var{x}}}{(5)}
\lineiii{\var{s}.count(\var{x})}
{return number of \var{i}'s for which \code{\var{s}[\var{i}] == \var{x}}}{}
\lineiii{\var{s}.index(\var{x})}
@@ -476,6 +478,7 @@
\stindex{del}
\withsubitem{(list method)}{%
\ttindex{append}%
+ \ttindex{extend}%
\ttindex{count}%
\ttindex{index}%
\ttindex{insert}%
@@ -509,6 +512,9 @@
The optional argument \var{i} defaults to \code{-1}, so that
by default the last item is removed and returned.
+\item[(5)] Raises an exception when \var{x} is not a list object. The
+\method{extend()} method is experimental and not supported by mutable types
+other than lists.
\end{description}