At unpickling time, some methods like :meth:`__getattr__`,
:meth:`__getattribute__`, or :meth:`__setattr__` may be called upon the
instance. In case those methods rely on some internal invariant being
- true, the type should implement :meth:`__getnewargs__` or
- :meth:`__getnewargs_ex__` to establish such an invariant; otherwise,
- neither :meth:`__new__` nor :meth:`__init__` will be called.
+ true, the type should implement :meth:`__new__` to establish such an
+ invariant, as :meth:`__init__` is not called when unpickling an
+ instance.
.. index:: pair: copy; protocol