bpo-33816: Remove outdated metaclass example (GH-7566)

(cherry picked from commit c2ccac7)

Co-authored-by: Andrés Delfino <[email protected]>

Author: miss-islington

Doc/reference/datamodel.rst

@@ -1918,46 +1918,14 @@ becomes the :attr:`~object.__dict__` attribute of the class object.
       Describes the implicit ``__class__`` closure reference
 
 
-Metaclass example
-^^^^^^^^^^^^^^^^^
+Uses for metaclasses
+^^^^^^^^^^^^^^^^^^^^
 
 The potential uses for metaclasses are boundless. Some ideas that have been
 explored include enum, logging, interface checking, automatic delegation,
 automatic property creation, proxies, frameworks, and automatic resource
 locking/synchronization.
 
-Here is an example of a metaclass that uses an :class:`collections.OrderedDict`
-to remember the order that class variables are defined::
-
-    class OrderedClass(type):
-
-        @classmethod
-        def __prepare__(metacls, name, bases, **kwds):
-            return collections.OrderedDict()
-
-        def __new__(cls, name, bases, namespace, **kwds):
-            result = type.__new__(cls, name, bases, dict(namespace))
-            result.members = tuple(namespace)
-            return result
-
-    class A(metaclass=OrderedClass):
-        def one(self): pass
-        def two(self): pass
-        def three(self): pass
-        def four(self): pass
-
-    >>> A.members
-    ('__module__', 'one', 'two', 'three', 'four')
-
-When the class definition for *A* gets executed, the process begins with
-calling the metaclass's :meth:`__prepare__` method which returns an empty
-:class:`collections.OrderedDict`.  That mapping records the methods and
-attributes of *A* as they are defined within the body of the class statement.
-Once those definitions are executed, the ordered dictionary is fully populated
-and the metaclass's :meth:`__new__` method gets invoked.  That method builds
-the new type and it saves the ordered dictionary keys in an attribute
-called ``members``.
-
 
 Customizing instance and subclass checks
 ----------------------------------------