- Leaf-cumulate-iter continues to suffer from the last point of >>51.
- Leaf-cumulate is an instance of gen-leaf-fold with a pair holding the 'proc' output and the new-leaf as accumulator, as seen on the alternate branch. There's no need to repeat the iteration code.
- Radix-cumulate-iter and its containing 'if' are ripe for replacement by level-1-fold.