code: def _check_fitted_params_keys(fitted_params):
      # ensure that the best_forecaster and best_score are in fitted_params
      assert "best_forecaster" in fitted_params.keys()
      assert "best_score" in fitted_params.keys()
  
imports: import numpy
  import pytest
  from sklearn.model_selection import ParameterGrid, ParameterSampler
  from sktime.datasets import load_airline, load_longley
  from sktime.forecasting.arima import ARIMA
  from sktime.forecasting.compose import TransformedTargetForecaster
  from sktime.forecasting.exp_smoothing import ExponentialSmoothing
  from sktime.forecasting.model_evaluation import evaluate
  from sktime.forecasting.model_selection import ForecastingGridSearchCV, ForecastingRandomizedSearchCV, ForecastingSkoptSearchCV
  from sktime.forecasting.model_selection._tune import BaseGridSearch
  from sktime.forecasting.naive import NaiveForecaster
  from sktime.forecasting.tests._config import TEST_N_ITERS, TEST_OOS_FHS, TEST_RANDOM_SEEDS, TEST_WINDOW_LENGTHS_INT
  from sktime.forecasting.trend import PolynomialTrendForecaster
  from sktime.performance_metrics.forecasting import MeanAbsolutePercentageError, MeanSquaredError
  from sktime.performance_metrics.forecasting.probabilistic import CRPS, PinballLoss
  from sktime.split import SingleWindowSplitter, SlidingWindowSplitter
  from sktime.tests.test_switch import run_test_for_class
  from sktime.transformations.series.detrend import Detrender
  from sktime.transformations.series.impute import Imputer
  from sktime.utils._testing.hierarchical import _make_hierarchical
  from sktime.utils.parallel import _get_parallel_test_fixtures
label_desc: Use image node_id 2 for calling a global function with example usage: _check_fitted_params_keys(fitted_params) without return types