// these functions will print the value of every node.
// traverse left subtree, process current node, traverse right subtree.
void BST::inorder(Node *current){
    if (!current)
        return;
    inorder(current->lchild);
    cout << current->data << endl;
    inorder(current->rchild);
}

// process current node, traverse left subree, traverse right subtree.
void BST::preorder(Node *current){

}

//traverse left subtree, traverse right subtree, process current node.
void BST::postorder(Node *current){

}