code: def test_call_backtest_naive_ensemble_local_models(self):
      ensemble = NaiveEnsembleModel([NaiveSeasonal(5), Theta(2, 5)])
      ensemble.fit(self.series1)
      assert ensemble.extreme_lags == (-10, -1, None, None, None, None)
      ensemble.backtest(self.series1)
  
imports: import numpy
  import pandas
  import pytest
  from darts import TimeSeries
  from darts.logging import get_logger
  from darts.models import ExponentialSmoothing, LinearRegressionModel, NaiveDrift, NaiveEnsembleModel, NaiveSeasonal, StatsForecastAutoARIMA, Theta
  from darts.tests.conftest import tfm_kwargs
  from darts.utils import timeseries_generation
label_desc: Use image node_id 6 for calling the TestEnsembleModels obj's underlying member method code with example usage: obj.test_call_backtest_naive_ensemble_local_models() without return types