new_contents: #!/usr/bin/env python3
  # -*- coding: utf-8 -*-
  
  from livemark.diff import _is_same_node, _next_noempty
  
  from wdom.tests.util import TestCase
  from wdom.parser import parse_html
  
  
  class TestSameNode(TestCase):
      def test_same_node(self):
          node1_src = '<h1>A</h1>'
          node1 = parse_html(node1_src)
          node2 = parse_html(node1_src)
          self.assertTrue(_is_same_node(node1.firstChild, node2.firstChild))
  
subject: Add test for diff