option_like_monad.py

class M:
    def __init__(self, val=None, exc=None):
        self.val = val
        self.exc = exc

    def __getattr__(self, item):
        if self.exc:
            return M(exc=self.exc)
        if hasattr(self.val, item):
            return M(getattr(self.val, item), self.exc)
        raise Exception(f'missed attr {item}')

    def __call__(self, *args, **kwargs):
        try:
            return M(exc=self.exc) if self.exc\
                else M(val=self.val(*args, **kwargs))
        except Exception as err:
            return M(exc=err)

    def unwrap(self):
        if self.exc:
            raise self.exc
        return self.val


class TheA:
    def a(self):
        return TheB()


class TheB:
    def b(self, raise_exception):
        if raise_exception:
            raise Exception('Something went wrong')
        return TheC()


class TheC:
    def c(self):
        return 42

a = M(TheA()).a
x = a().b(raise_exception=False).c().unwrap()
print(x)