public static int getParentOrder(int nodeOrder) {
        return (nodeOrder - 1) >> 1;
    }
@Test
    public void testGetParentOrder() {
        assertEquals(0, MerkleTreeUtil.getParentOrder(1));
        assertEquals(0, MerkleTreeUtil.getParentOrder(2));
        assertEquals(1, MerkleTreeUtil.getParentOrder(3));
        assertEquals(1, MerkleTreeUtil.getParentOrder(4));
        assertEquals(2, MerkleTreeUtil.getParentOrder(5));
        assertEquals(2, MerkleTreeUtil.getParentOrder(6));
    }