Create a Scala 3 Function for the following: def postOrderToList(tree: BinaryTree[A]): List[A]: Returns a list of all items in tree, ordered from left,right,Root. For example, given the tree below, return List(4, 5, 3, 7, 8, 6, 2, 9, 1). Hint: a Helper may be useful. Use this definition of a BinaryTree:.