SF Bug 645777: list.extend() works with any iterable and is no longer

experimental.

Doc/lib/libstdtypes.tex

@@ -946,9 +946,7 @@ Notes:
   Use of this misfeature has been deprecated since Python 1.4,
   and became an error with the introduction of Python 2.0.
 
-\item[(2)] Raises an exception when \var{x} is not a list object.  The
-  \method{extend()} method is experimental and not supported by
-  mutable sequence types other than lists.
+\item[(2)] Raises an exception when \var{x} is not an iterable object.
 
 \item[(3)] Raises \exception{ValueError} when \var{x} is not found in
   \var{s}.

Objects/listobject.c

@@ -2055,7 +2055,7 @@ list_nohash(PyObject *self)
 PyDoc_STRVAR(append_doc,
 "L.append(object) -- append object to end");
 PyDoc_STRVAR(extend_doc,
-"L.extend(sequence) -- extend list by appending sequence elements");
+"L.extend(iterable) -- extend list by appending elements from the iterable");
 PyDoc_STRVAR(insert_doc,
 "L.insert(index, object) -- insert object before index");
 PyDoc_STRVAR(pop_doc,