Add in the numeric add/sub methods to disable.

def _add_numeric_methods_add_sub_disabled(cls):
        """
        Add in the numeric add/sub methods to disable.
        """
        cls.__add__ = make_invalid_op('__add__')
        cls.__radd__ = make_invalid_op('__radd__')
        cls.__iadd__ = make_invalid_op('__iadd__')
        cls.__sub__ = make_invalid_op('__sub__')
        cls.__rsub__ = make_invalid_op('__rsub__')
        cls.__isub__ = make_invalid_op('__isub__')