code: def __getitem__(
      self, idx
  ) -> Tuple[
      np.ndarray,
      Optional[np.ndarray],
      Optional[np.ndarray],
      Optional[np.ndarray],
      np.ndarray,
  ]:
      (
          past_target,
          past_covariate,
          static_covariate,
          future_target,
      ) = self.ds_past[idx]
      _, future_covariate, _, _ = self.ds_future[idx]
      return (
          past_target,
          past_covariate,
          future_covariate,
          static_covariate,
          future_target,
      )
  
imports: from typing import Optional, Sequence, Tuple, Union
  import numpy
  from darts import TimeSeries
  from .shifted_dataset import GenericShiftedDataset
  from .training_dataset import DualCovariatesTrainingDataset, FutureCovariatesTrainingDataset, MixedCovariatesTrainingDataset, PastCovariatesTrainingDataset, SplitCovariatesTrainingDataset
  from .utils import CovariateType
label_desc: Use image node_id 3 for calling the SplitCovariatesSequentialDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: past_target,  past_covariate,  future_covariate,  static_covariate,  future_target