[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import attr
>>> attr.__version__
'17.3.0'
>>> from copy import deepcopy
>>> @attr.s(slots=True)
... class Han(object):
...     __weakref__ = attr.ib(init=False, hash=False, repr=False, cmp=False)
... 
>>> h = Han()
>>> o = deepcopy(h)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/usr/lib/python2.7/copy.py", line 336, in _reconstruct
    y.__setstate__(state)
  File "/usr/local/lib/python2.7/dist-packages/attr/_make.py", line 432, in slots_setstate
    __bound_setattr(name, value)
AttributeError: attribute '__weakref__' of 'Han' objects is not writable