Convert dict to dict with attribut

jdict.py

class Jdict(dict):
    def __new__(cls, obj):
        if isinstance(obj, dict):
            instance = super().__new__(cls)
            instance.update(obj)
            return instance
        elif isinstance(obj, list):
            return [cls(i) for i in obj]
        else:
            return obj

    def __getattr__(self, name: str):
        if name in self:
            return Jdict(self[name])
        else:
            return f"?{name}?"

if __name__=="__main__":

    x=Jdict(dict(a=12))
    print(x)    # -> {'a': 12}
    print(x.a)  # -> 12
    print(x.b)  # -> '?b?'