def __new__(cls, mapper=None):
<EOL>if not hasattr(cls, '<STR_LIT>'):<EOL><INDENT>raise exceptions.IncompleteController()<EOL><DEDENT>return super(Controller, cls).__new__(cls, mapper)<EOL>
Prefilter controller class instantiation.  Prohibits
instantiation of a Controller subclass unless the class has
the `wsgi_name` attribute set.