λ> mkFt [1..5]
Deep (Sum 5) (Four 5 4 3 2) Empty (One 1)
λ> mkFt [1..6]
Deep (Sum 6) (Two 6 5) (Single (Node3 (Sum 3) 4 3 2)) (One 1)
λ> mkFt [1..8]
Deep (Sum 8)
(Four 8 7 6 5)
(Single (Node3 (Sum 3) 4 3 2))
(One 1)
λ> mkFt [1..9]
Deep (Sum 9)
(Two 9 8)
(Deep (Sum 6)
(One (Node3 (Sum 3) 7 6 5))
Empty
(One (Node3 (Sum 3) 4 3 2)))
(One 1)