c++ languages

Question 2. (10) Consider the given code and perform the following operations: a) Find out the missing statement for tree preorder traversal. b) Convert the code to perform tree traversal iteratively. public void preOrder(Tree root) { if (root == null) return; st.add(root); while (!stk.empty) { Tree node = stk.pop(); System.out.print(node.data + " "); if (node.left != null) stk.push(node.left); }