greatly 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