gistfile1.py

class Foo:
    _answer = 42
    @property
    def answer(self):
        print('getting!')
        return self._answer

    @answer.setter
    def answer(self, new_answer):
        print('setting!')
        self._answer = new_answer


f = Foo()
print(f.answer)
f.answer = 23
print(f.answer)