def setUp(self):
        """
        Create a fresh new L{Values} subclass for each unit test to use.  Since
        L{Values} is stateful, re-using the same subclass across test methods
        makes exercising all of the implementation code paths difficult.
        """
        class STATUS(Values):
            OK = ValueConstant("200")
            NOT_FOUND = ValueConstant("404")

        self.STATUS = STATUS

        Create a fresh new L{Values} subclass for each unit test to use.  Since
        L{Values} is stateful, re-using the same subclass across test methods
        makes exercising all of the implementation code paths difficult.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_constants.py