simplifies writing classes that need to be substitutable for dictionaries (such
as the shelve module).
-This also module defines a class, :class:`UserDict`, that acts as a wrapper
+This module also defines a class, :class:`UserDict`, that acts as a wrapper
around dictionary objects. The need for this class has been largely supplanted
by the ability to subclass directly from :class:`dict` (a feature that became
available starting with Python version 2.2). Prior to the introduction of