code: def fit(self, series: TimeSeries):
      super().fit(series)
      self._assert_univariate(series)
      series = self.training_series
  
      if self.infer_seasonal_periods:
          seasonality = _seasonality_from_freq(series)
          self.kwargs["seasonal_periods"] = seasonality
          self.seasonal_periods = seasonality
  
      model = self._create_model()
      fitted_model = model.fit(series.values())
      self.model = fitted_model
  
      return self
  
imports: from abc import ABC, abstractmethod
  from typing import List, Optional, Tuple, Union
  import numpy
  from scipy.special import inv_boxcox
  from tbats import BATS
  from tbats import TBATS
  from darts.logging import get_logger
  from darts.models.forecasting.forecasting_model import LocalForecastingModel
  from darts.timeseries import TimeSeries
label_desc: Use image node_id 3 for calling the _BaseBatsTbatsModel obj's underlying member method code with example usage: obj.fit(series) and returns: self