t0 _: Tuple([]) = None
t1 _: Tuple([Int]) = None
_ = t0(()) # OK
_ = t0((1,)) # OK
_ = t1(()) # ERR
_ = t1((1,)) # OK
_ = t1((1, 2)) # OK
_ as Iterator(Int) = iter((1, 2)) # OK
_ as Iterator((Int, Int)) = iter([(1, 2)]) # OK
_ as Iterator((Int, Int)) = iter((1, 2)) # ERR