Enumerations

def __new__(self, name, bases, classdict):
    members = []
    keys = {}
    choices = OrderedDict()
    for key, value in classdict.items():
        if key.startswith("__"):
            continue
        members.append(key)
        if isinstance(value, tuple):
            value, alias = value
            keys[alias] = key
        else:
            alias = None
        keys[alias or key] = key
        choices[alias or key] = value

    for k, v in keys.items():
        classdict[v] = k

    classdict["__choices__"] = choices
    classdict["__members__"] = members

    # Note: Differences between Python 2.x and Python 3.x force us to
    # explicitly use unicode here, and to explicitly sort the list. In
    # Python 2.x, class members are unordered and so the ordering will
    # vary on different systems based on internal hashing. Without this
    # Django will continually require new no-op migrations.
    classdict["choices"] = tuple(
        (str(k), str(v))
        for k, v in sorted(choices.items(), key=operator.itemgetter(0))
    )

    return type.__new__(self, name, bases, classdict)

@classmethod
def __prepare__(self, name, bases):
    return OrderedDict()