code: def update(self, modelResult):
      
      self.__writer.append(self.__inferenceShifter.shift(modelResult))
docs: Queue up the T(i+1) prediction value and emit a T(i)
      input/prediction pair, if possible.  E.g., if the previous T(i-1)
      iteration was learn-only, then we would not have a T(i) prediction in our
      FIFO and would not be able to emit a meaningful input/prediction
      pair.
  
      modelResult:    An opf_utils.ModelResult object that contains the model input
                      and output for the current timestep.