public void insertIterative(E e) {
        Node newNode = new Node();
        newNode.data = e;
        newNode.left = null;
        newNode.right = null;
        Node currentNode;
        if (root == null) {
            root = newNode;
        } else {
            currentNode = root;
            boolean inserted = false;
            while (!inserted) {
                if (newNode.data.compareTo(currentNode.data) < 0) {
                    //go left
                    if (currentNode.left == null) {
                        currentNode.left = newNode;

                        inserted = true;
                    } else {
                        currentNode = currentNode.left;
                    }
                } else {
                    //go right
                    if (currentNode.right == null) {
                        currentNode.right = newNode;
                        inserted = true;
                    } else {
                        currentNode = currentNode.right;
                    }

                }
            }
        }
    }