#835521: Add index entries for various pickle-protocol methods and attributes

Doc/library/pickle.rst

@@ -463,6 +463,11 @@ can do what they want. [#]_
 Pickling and unpickling extension types
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+.. index::
+   single: __reduce__() (pickle protocol)
+   single: __reduce_ex__() (pickle protocol)
+   single: __safe_for_unpickling__ (pickle protocol)
+
 When the :class:`Pickler` encounters an object of a type it knows nothing about
 --- such as an extension type --- it looks in two places for a hint of how to
 pickle it.  One alternative is for the object to implement a :meth:`__reduce__`
@@ -541,6 +546,10 @@ unpickling as described above.
 Pickling and unpickling external objects
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+.. index::
+   single: persistent_id (pickle protocol)
+   single: persistent_load (pickle protocol)
+
 For the benefit of object persistence, the :mod:`pickle` module supports the
 notion of a reference to an object outside the pickled data stream.  Such
 objects are referenced by a "persistent id", which is just an arbitrary string
@@ -630,6 +639,10 @@ with the :meth:`noload` method on the Unpickler.
 Subclassing Unpicklers
 ----------------------
 
+.. index::
+   single: load_global() (pickle protocol)
+   single: find_global() (pickle protocol)
+
 By default, unpickling will import any class that it finds in the pickle data.
 You can control exactly what gets unpickled and what gets called by customizing
 your unpickler.  Unfortunately, exactly how you do this is different depending