public static int getNodesOnLevel(int level) {
        return 1 << level;
    }
@Test
    public void testGetNodesOnLevel() {
        assertEquals(1, MerkleTreeUtil.getNodesOnLevel(0));
        assertEquals(2, MerkleTreeUtil.getNodesOnLevel(1));
        assertEquals(4, MerkleTreeUtil.getNodesOnLevel(2));
        assertEquals(8, MerkleTreeUtil.getNodesOnLevel(3));
        assertEquals(16, MerkleTreeUtil.getNodesOnLevel(4));
    }