code: def test_regression_model(self, mode):
      lags = 4
      models = [
          RegressionModel(lags=lags, multi_models=mode),
          RegressionModel(
              lags=lags, model=LinearRegression(), multi_models=mode
          ),
          RegressionModel(
              lags=lags,
              model=RandomForestRegressor(),
              multi_models=mode,
          ),
          RegressionModel(
              lags=lags,
              model=HistGradientBoostingRegressor(),
              multi_models=mode,
          ),
      ]
  
      for model in models:
          model.fit(series=self.sine_univariate1)
          assert len(model.lags.get("target")) == lags
          model.predict(n=10)
  
imports: import copy
  import functools
  import itertools
  import math
  from unittest.mock import patch
  import numpy
  import pandas
  import pytest
  from sklearn.ensemble import HistGradientBoostingRegressor, RandomForestRegressor
  from sklearn.linear_model import LinearRegression
  import darts
  from darts import TimeSeries
  from darts.dataprocessing.encoders import FutureCyclicEncoder, PastDatetimeAttributeEncoder
  from darts.logging import get_logger
  from darts.metrics import mae, rmse
  from darts.models import CatBoostModel, LightGBMModel, LinearRegressionModel, NotImportedModule, RandomForest, RegressionModel, XGBModel
  from darts.utils import timeseries_generation
  from darts.utils.multioutput import MultiOutputRegressor
label_desc: Use image node_id 17 for calling the TestRegressionModels obj's underlying member method code with example usage: obj.test_regression_model(mode) without return types