__setslice__(self, i, j, sequence)
Called to implement assignment to self[i:j]. Same
notes for i and j as for __getslice__().
This method is deprecated. If no __setslice__() is found, or for
extended slicing of the form self[i:j:k], a slice
object is created, and passed to __setitem__(), instead of
__setslice__() being called.