cons4 :: (Serial a, Serial b, Serial c, Serial d) =>
  (a -> b -> c -> d -> e) -> Series e
cons4 f = cons f >< series >< series >< series >< series
cons4 :: (Serial a, Serial b, Serial c, Serial d) =>
  (a -> b -> c -> d -> e) -> Series e
cons4 f = cons f >< series >< series >< series >< series
cons4 f = cons f >< series >< series >< series >< series