def METHOD_NAME(self):
    class BasePerson(HasTraits):
        married = PrefixMap({"yes": 1, "yeah": 1, "no": 0, "nah": 0})
        default_calls = Int(0)
        def _married_default(self):
            self.default_calls += 1
            return "nah"
    class Person(BasePerson):
        def _married_default(self):
            self.default_calls += 1
            return "yes"
    p = Person()
    self.assertEqual(p.married, "yes")
    self.assertEqual(p.married_, 1)
    self.assertEqual(p.default_calls, 1)