def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def test_supertype(self):
        self.assert_(isinstance(None, NullType))
        self.assert_(isinstance(Optional('a'), NullType))
        self.assert_(isinstance(NotPassed, NotPassedType))
        self.assert_(isinstance(NotPassed, NullType))