bpo-9372: Deprecate several __getitem__ methods (GH-8609)

The __getitem__ methods of DOMEventStream, FileInput,
and FileWrapper classes ignore their 'index' parameters
and return the next item instead.

Doc/library/fileinput.rst

@@ -169,6 +169,9 @@ available for subclassing as well:
    .. deprecated-removed:: 3.6 3.8
       The *bufsize* parameter.
 
+   .. deprecated:: 3.8
+      Support for :meth:`__getitem__` method is deprecated.
+
 
 **Optional in-place filtering:** if the keyword argument ``inplace=True`` is
 passed to :func:`fileinput.input` or to the :class:`FileInput` constructor, the

Doc/library/wsgiref.rst

@@ -173,6 +173,8 @@ also provides these miscellaneous utilities:
       for chunk in wrapper:
           print(chunk)
 
+   .. deprecated:: 3.8
+      Support for :meth:`sequence protocol <__getitem__>` is deprecated.
 
 
 :mod:`wsgiref.headers` -- WSGI response header tools

Doc/library/xml.dom.pulldom.rst

@@ -100,6 +100,8 @@ DOMEventStream Objects
 
 .. class:: DOMEventStream(stream, parser, bufsize)
 
+   .. deprecated:: 3.8
+      Support for :meth:`sequence protocol <__getitem__>` is deprecated.
 
    .. method:: getEvent()
 

Doc/whatsnew/3.8.rst

@@ -154,6 +154,15 @@ Build and C API Changes
 
   (Contributed by Antoine Pitrou in :issue:`32430`.)
 
+* The :meth:`__getitem__` methods of :class:`xml.dom.pulldom.DOMEventStream`,
+  :class:`wsgiref.util.FileWrapper` and :class:`fileinput.FileInput` have been
+  deprecated.
+
+  Implementations of these methods have been ignoring their *index* parameter,
+  and returning the next item instead.
+
+  (Contributed by Berker Peksag in :issue:`9372`.)
+
 
 Deprecated
 ==========