code: def calibration_stimulus(self, mode):
          
          if mode == 'tone':
              return self.tone_calibrator.stimulus
          elif mode =='noise':
              return self.bs_calibrator.stimulus
docs: Gets the stimulus model for calibration
  
          :param mode: Type of stimulus to get: tone or noise
          :type mode: str
          :returns: :class:`StimulusModel<sparkle.stim.stimulus_model.StimulusModel>`