自动实现字典嵌套

Vividict.py

class Vividict(dict):
    def __missing__(self, key):
        value = self[key] = type(self)()
        return value

    def walk(self):
        for key, value in self.items():
            if isinstance(value, Vividict):
                for tup in value.walk():
                    yield (key,) + tup
            else:
                yield key, value