99 Elm Problems/Problem 72

Given a tree, construct the bottom-up order sequence of the tree nodes. In bottom-up sequence all child nodes must be shown before any of its parent nodes. The bottom-up sequence of tree5 is "gfcdeba"

# # # THIS IS A STUB # # #

Example in Elm:
import Html exposing (text)
import List

f : Int -> Int
-- your implementation goes here

main = text (toString (f 0))