code: def test_get_history():
      tracker = metrics_tracking.MetricsTracker()
      tracker.update("new_metric", 0.5, step=0)
      tracker.update("new_metric", 1.5, step=1)
      tracker.update("new_metric", 2.0, step=2)
      assert tracker.get_history("new_metric") == [
          metrics_tracking.MetricObservation(0.5, 0),
          metrics_tracking.MetricObservation(1.5, 1),
          metrics_tracking.MetricObservation(2.0, 2),
      ]
      with pytest.raises(ValueError, match="Unknown metric"):
          tracker.get_history("another_metric")
  
imports: import random
  import numpy
  import pytest
  from keras_tuner.backend.keras import losses
  from keras_tuner.backend.keras import metrics
  from keras_tuner.engine import metrics_tracking
label_desc: Use image node_id 6 for calling a global function with example usage: test_get_history() without return types