On Sep 29, 2010, at 11:29 PM, Terry Reedy wrote: > I do not understand this. List.__add__ is currently *more* restrictive than set ops in that it will not even accept a 'frozenlist' (aka tuple). Sorry, that should have been __iadd__(). >>> s = range(5) >>> s += 'abc' >>> s [0, 1, 2, 3, 4, 'a', 'b', 'c'] Raymond