classJust(object): def__init__(self, a): object.__setattr__(self, 'a', a)
def__call__(self, default=None): a = object.__getattribute__(self, 'a') return default if a == Noneelse a
def__getattribute__(self, key): a = object.__getattribute__(self, 'a') if isinstance(a, dict) and (key in a): return Just(a[key]) else: return Just(None)