Namespace.py

class Namespace:

    __slots__ = '_Namespace__names'

    def __init__(self, **items):
        self.__names = dict(**items)

    def __setattr__(self, key, value):
        if key in self.__slots__:
            super().__setattr__(key, value)
        else:
            self.__names[key] = value

    def __getattr__(self, item):
        try:
            return self.__names[item]
        except KeyError:
            raise AttributeError(item) from None

    def __repr__(self):
        return '{}({})'.format(self.__class__.__name__, self.__names)


ns = Namespace()
ns.a1 = 'value a1'
ns.b1 = Namespace(b11='value b11')
ns.b1.b12 = 'value b12'

print(ns)
# -> Namespace({'b1': Namespace({'b12': 'value b12', 'b11': 'value b11'}), 'a1': 'value a1'})
pr1int(ns.a1)
# -> value a1
print(ns.b1.b11)
# -> value a1
print(ns.b1.b12)
# -> value a1

Also see https://docs.python.org/3/library/types.html?highlight=simplenamespace#types.SimpleNamespace