54     def __setitem__(cls, key, value):  argument
58             key += MUTABLE
59         setattr(cls, key, value)
61     def __getmutable__(cls, key, readonly=False):  argument
62         nkey = key + MUTABLE
73             print("Warning: Doing a copy because %s is a mutable type." % key, file=cls.__warn__)
83     def __getreadonly__(cls, key, default=__getmarker__):  argument
87         return cls.__getitem__(key, default, True)
89     def __getitem__(cls, key, default=__getmarker__, readonly=False):  argument
92                 value = getattr(cls, key)
94                 value = cls.__getmutable__(key, readonly)
98                 raise AttributeError("key %s does not exist." % key)
107     def __delitem__(cls, key):  argument
108         cls.__setitem__(key, cls.__marker__)
110     def __revertitem__(cls, key):  argument
111         if key not in cls.__dict__:
112             key += MUTABLE
113         delattr(cls, key)
115     def __contains__(cls, key):  argument
116         return cls.has_key(key)
118     def has_key(cls, key):  argument
119         value = cls.__getreadonly__(key, cls.__marker__)
125         for key in dir(cls):
126             if key.startswith("__"):
129             if key.endswith(MUTABLE):
130                 key = key[:-len(MUTABLE)]
133                 yield key
137                     value = cls.__getreadonly__(key)
139                     value = cls[key]
146                 yield (key, value)