code: def testRemovedFields(self):
      a = sc_pb.ResponseObservation(
          observation=sc_pb.Observation(
              game_loop=1,
              score=score_pb2.Score(),
              alerts=[sc_pb.AlertError, sc_pb.MergeComplete],
          )
      )
      b = sc_pb.ResponseObservation(
          observation=sc_pb.Observation(alerts=[sc_pb.AlertError])
      )
      diff = proto_diff.compute_diff(a, b)
      self.assertIsNotNone(diff)
      self.assertLen(diff.removed, 3, diff)
      self.assertEqual(str(diff.removed[0]), "observation.alerts[1]")
      self.assertEqual(str(diff.removed[1]), "observation.game_loop")
      self.assertEqual(str(diff.removed[2]), "observation.score")
      self.assertEqual(diff.removed, diff.all_diffs())
      self.assertEqual(
          diff.report(),
          "Removed observation.alerts[1].\n"
          "Removed observation.game_loop.\n"
          "Removed observation.score.",
      )
  
imports: from absl.testing import absltest
  from pysc2.lib import proto_diff
  from s2clientprotocol import sc2api_pb2
  from s2clientprotocol import score_pb2
label_desc: Use image node_id 5 for calling the ProtoDiffTest obj's underlying member method code with example usage: obj.testRemovedFields() without return types