Please use plait in Racket

The following Tree datatype implements a binary tree with a number in each node and leaf: (define-type Tree (leaf [val : Number]) (node [val : Number] [left : Tree] [right : Tree]))

A) Contains?

Implement the function contains?, which takes a tree and a number and returns #t if the number is in the tree, #f otherwise.

Example: (contains? (node 5 (leaf 6) (leaf 7)) 6) should produce #t. The second argument to the contains? function is along for the ride.

B) Big Leaves?

Implement the function big-leaves?, which takes a tree and returns #t if every leaf is bigger than the sum of numbers in the path of nodes from the root that reaches the leaf.

Examples: (big-leaves? (node 5 (leaf 6) (leaf 7))) should produce #t, while (bigleaves? (node 5 (node 2 (leaf 8) (leaf 6)) (leaf 7))) should produce #f (since 6 is smaller than 5 plus 2). The big-leaves? function should be a thin wrapper on another function, perhaps bigger-leaves?, that accumulates a sum of node values.