testReverseOrderTraverse() {
    const tree = new AvlTree((a, b) => a - b);

    const NUM_TO_INSERT = 2000;
    const NUM_TO_REMOVE = 500;

    // Insert ints into tree out of order
    for (let i = 0; i < NUM_TO_INSERT; i += 1) {
      tree.add(i);
    }

    // Remove valuse
    for (let i = 0; i < NUM_TO_REMOVE; i += 1) {
      tree.remove(i);
    }

    let i = NUM_TO_INSERT - 1;
    tree.reverseOrderTraverse((value) => {
      assertEquals(value, i);
      i -= 1;
    });
    assertEquals(i, NUM_TO_REMOVE - 1);
  }
This test verifies that we can insert values into and remove values from
the AvlTree and traverse the tree in reverse order using the
reverseOrderTraverse routine.