Tree.

reverse(map)

Reverses the order of keys in the map-like object.

$ cat letters.yaml
a: The letter A
b: The letter B
c: The letter C
$ ori Tree.reverse letters.yaml
c: The letter C
b: The letter B
a: The letter A
g a The letter A ->a a b The letter B ->b b c The letter C ->c c
g c The letter C ->c c b The letter B ->b b a The letter A ->a a
Input map
With reversed keys

After sorting by date with sort, it can be useful to reverse that order to get things in reverse chronological order.

For a deep version that affects all levels of a tree, use deepReverse