new_contents: from __future__ import print_function, unicode_literals, division
  
  import unittest
  
  import s2  # SWIG wrapped original C++ implementation
  import s2sphere.sphere as sphere
  
  
  class TestCellId(unittest.TestCase):
  
      def test_cellid(self):
          lat, lon = (33, -122)
          pyc = sphere.CellId.from_lat_lon(sphere.LatLon.from_degrees(lat, lon))
          cc = s2.S2CellId.FromLatLng(s2.S2LatLng.FromDegrees(lat, lon))
          print(pyc.id(), cc.id())
          self.assertEqual(pyc.id(), cc.id())
  
      def test_cellid_level(self, level=12):
          lat, lon = (33, -122)
          pyc = (sphere.CellId
                 .from_lat_lon(sphere.LatLon.from_degrees(lat, lon))
                 .parent(level))
          cc = (s2.S2CellId
                .FromLatLng(s2.S2LatLng.FromDegrees(lat, lon))
                .parent(level))
          print(pyc.id(), cc.id())
          self.assertEqual(pyc.id(), cc.id())
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: add test cases that compare the two implementations directly