code: def test_metrics_for_mode(self):
      history = trax_history.History()
      history.append("train", "metric1", 1, 0.1)
      history.append("train", "metric2", 2, 0.2)
      self.assertEqual(
          history.metrics_for_mode("train"), ["metric1", "metric2"]
      )
  
file_path: trax/trax/supervised/history_test.py
imports: from absl.testing import absltest
  from trax.supervised import history
label_desc: Use image node_id 5 for calling the HistoryTest obj's underlying member method code with example usage: obj.test_metrics_for_mode() without return types