Python에서 순서가 지정된 기본 사전을 만드는 방법은 무엇입니까?

<code class="python">from collections import OrderedDict, Callable

class DefaultOrderedDict(OrderedDict):
    def __init__(self, default_factory=None, *a, **kw):
        if (default_factory is not None and not isinstance(default_factory, Callable)):
            raise TypeError('first argument must be callable')
        OrderedDict.__init__(self, *a, **kw)
        self.default_factory = default_factory

    def __getitem__(self, key):
        try:
            return OrderedDict.__getitem__(self, key)
        except KeyError:
            return self.__missing__(key)

    def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        self[key] = value = self.default_factory()
        return value</code>

<code class="python">ordered_default_dict = DefaultOrderedDict(lambda: 0)
ordered_default_dict['key1'] = 1
ordered_default_dict['key2'] = 2</code>

<code class="python">print(ordered_default_dict['missing_key'])  # Output: 0</code>