Gotta do this in racket with plait language and nothing else. Appreciate it!

Implement the function positive-trees?, which takes a list of trees and returns \#t if every member of the list is a positive tree, where a positive tree is one whose numbers sum to a positive value. Hint 1: This function takes a list, not a tree, so don't try to use the template for a tree function. Hint 2: Use your sum function as a helper. Hint 3: (positive-trees? empty) should produce \#t, because there's no tree in the empty list whose numbers sum to 0 or less. More examples