code: def __call__(self):
      self.seek(self.model.nobs - 1)
      # Perform backwards smoothing iterations
      for i in range(self.model.nobs - 1, -1, -1):
          next(self)
  
file_path: statsmodels/statsmodels/tsa/statespace/_pykalman_smoother.py
imports: import numpy
label_desc: Use image node_id 4 for calling the _KalmanSmoother obj's underlying member method code with example usage: obj.__call__() without return types