--
(|->) :: (a, b) -> a -> Transition b a
(s1, l) |-> s2 = Transition (State s1) l (State s2)
(|->) :: (a, b) -> a -> Transition b a
(s1, l) |-> s2 = Transition (State s1) l (State s2)
(s1, l) |-> s2 = Transition (State s1) l (State s2)