#17040: document that shelve.open() and the Shelf object can be used as context managers.  Initial patch by Berker Peksag.
#16128: clarify that instances of user-defined classes compare equal with themselves.
#16128: merge with 3.2.
#16128: merge with 3.3.
Issue #1783: Remove declarations of nonexistent private variables.
Issue #1783: Remove declarations of nonexistent private variables.
Issue #1783: Remove declarations of nonexistent private variables.