docstr: Differentiate the series self.d times
docstr_tok: ["Differentiate","the","series","self.d","times"]
code: def _differentiate_series(self, series: TimeSeries) -> TimeSeries:
      """Differentiate the series self.d times"""
      for _ in range(self.d):
          series = TimeSeries.from_dataframe(
              df=series.pd_dataframe(copy=False).diff().dropna(),
              static_covariates=series.static_covariates,
              hierarchy=series.hierarchy,
          )
      return series
  
file_path: darts/darts/models/forecasting/varima.py
imports: from typing import Optional
  import numpy
  import pandas
  from statsmodels.tsa.api import VARMAX
  from darts.logging import get_logger, raise_if
  from darts.models.forecasting.forecasting_model import TransferableFutureCovariatesLocalForecastingModel
  from darts.timeseries import TimeSeries
label_desc: Use image node_id 2 for calling the VARIMA obj's underlying member method code with example usage: obj._differentiate_series(series) and returns: series