code: def test_predict_interval_output_when_forecaster_is_LinearRegression_steps_is_2_in_sample_residuals_False_exog_and_transformer():
      """
      Test output of predict_interval when regressor is LinearRegression,
      2 steps are predicted, using out-sample residuals, exog is included and both
      inputs are transformed.
      """
      forecaster = ForecasterAutoregMultiVariate(
          regressor=LinearRegression(),
          steps=2,
          level="l1",
          lags=3,
          transformer_series=StandardScaler(),
          transformer_exog=transformer_exog,
      )
      forecaster.fit(series=series, exog=exog)
      forecaster.out_sample_residuals = forecaster.in_sample_residuals
      results = forecaster.predict_interval(
          steps=2,
          exog=exog_predict,
          n_boot=4,
          in_sample_residuals=False,
      )
      expected = pd.DataFrame(
          data=np.array(
              [
                  [0.61820497, 0.39855187, 0.67329092],
                  [0.41314101, 0.17729748, 0.81780586],
              ]
          ),
          columns=["l1", "lower_bound", "upper_bound"],
          index=pd.RangeIndex(start=50, stop=52),
      )
  
      pd.testing.assert_frame_equal(expected, results)
  
file_path: skforecast/skforecast/ForecasterAutoregMultiVariate/tests/test_predict_interval.py
imports: import numpy
  import pandas
  from skforecast.ForecasterAutoregMultiVariate import ForecasterAutoregMultiVariate
  from sklearn.linear_model import LinearRegression
  from sklearn.compose import ColumnTransformer
  from sklearn.preprocessing import StandardScaler
  from sklearn.preprocessing import OneHotEncoder
  from .fixtures_ForecasterAutoregMultiVariate import series
  from .fixtures_ForecasterAutoregMultiVariate import exog
  from .fixtures_ForecasterAutoregMultiVariate import exog_predict
label_desc: Use image node_id 2 for calling a global function with example usage: test_predict_interval_output_when_forecaster_is_LinearRegression_steps_is_2_in_sample_residuals_False_exog_and_transformer() without return types