Walking Trees Backwards

[Bernard Devlin]

Oops, forgot to include an example

input =

task1
    task1.a
    task1.b
        task1.b.1
task2
    task2.a
        task2.a.1
    task2.b
    task2.c
task3

output =
        task1.b.1
        task2.a.1
    task1.a
    task1.b
    task2.a
    task2.b
    task2.c
task1
task2
task3

Bernard