Looking for help in plait language on racket. Thanks!

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])) 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