type() bug?

example.py

class NS:

    PASSTHRU = frozenset(('__name__', '__qualname__', '__doc__', '__module__'))

    def __init__(self, data=None):
        if data is None:
            data = {}
        self.data = data

    def __setitem__(self, name, value):
        if name in self.PASSTHRU:
            self.data[name] = value
        elif isinstance(value, str):
            self.data[name] = value
        else:
            raise TypeError

    def __getitem__(self, name):
        if name in self.PASSTHRU:
            return self.data[name]
        elif name in self.data:
            return self.data[name]
        else:
            self.data[name] = name
            return self.data[name]


class Meta(type):

    @classmethod
    def __prepare__(mcls, name, bases):
        return NS()

    def __new__(mcls, name, bases, ns):
        classdict = ns.data
        return type.__new__(mcls, name, bases, classdict)


class Def(metaclass=Meta):
    pass


class Example(Def):
    a = 'a'
    b = 'b'
    c = 'c'

assert Example.a == 'a'
assert Example.b == 'b'
assert Example.c == 'c'

BrokenExample1 = type('BrokenExample1', (Def, ), NS({'x': 'x'}))
# Traceback (most recent call last):
#   File "example.py", line 53, in <module>
#     BrokenExample1 = type('BrokenExample1', (Def, ), NS({'x': 'x'}))
# TypeError: type() argument 3 must be dict, not NS

BrokenExample2 = type('BrokenExample2', (Def, ), {'x': 'x'})
# Traceback (most recent call last):
#   File "example.py", line 58, in <module>
#      BrokenExample2 = type('BrokenExample2', (Def, ), {'x': 'x'})
#   File "example.py", line 35, in __new__
#      classdict = ns.data
# AttributeError: 'dict' object has no attribute 'data'

Yes I've figured it out... on line 52 I should have used Meta...