- disallow object parameter of type "switch" to avoid possible confusion between (a) providing a value for the o.p., (b) calling it as a setter, and (c) calling it as a getter. For providing a value, no arg is used for switch. For calling a setter, it is necessary to provide a value even for a switch. - disallow type "switch" in setter definiton (use boolean instead) - disallow type "switch" for positional arguments (use boolean instead) - extended regression test