This module defines a class that acts as a wrapper around
list objects. It is a useful base class for
your own list-like classes, which can inherit from
them and override existing methods or add new ones. In this way one
can add new behaviours to lists.
Return a class instance that simulates a list. The instance's
contents are kept in a regular list, which is accessible via the
data attribute of UserList instances. The instance's
contents are initially set to a copy of list, defaulting to the
empty list []. list can be either a regular Python list,
or an instance of UserList (or a subclass).
In addition to supporting the methods and operations of mutable
sequences (see section 2.1.5), UserList instances
provide the following attribute: