foldlr (*) [1,2,3,4,5,6] == [6,10,12]
foldlr (+) [2,3,4,2,2,3,1] == [3,6,6]

sumMinBoth [2,3,4,2,2,3,1] [3,2,1,5,1,2] == 8
sumMinBoth [1,2,3,3] [3,3,4,5] == 6 

renameTree (Leaf 3.14) == Leaf 1
renameTree (Node "abc" (Node "xyz" (Leaf "abc") (Leaf ("ab"++"c"))) (Leaf "uv")) == (Node 1 (Node 2 (Leaf 1) (Leaf 1)) (Leaf 3)) {-corr.-}

mRT (Leaf 3.14) == Leaf 1
mRT (Node "abc" (Node "xyz" (Leaf "abc") (Leaf ("ab"++"c"))) (Leaf "uv")) == (Node 1 (Node 2 (Leaf 1) (Leaf 1)) (Leaf 3)) {-corr.-}