code: def scaled_exposure_time(self):
          
          if self._data_count_unit == 'ADU':
              exp_time = self.ccd_gain * self.exposure_time
          else:
              exp_time = self.exposure_time
          return exp_time
docs: scaled "effective" exposure time of IID counts. This can be used by lenstronomy to estimate the Poisson errors
          keeping the assumption that the counts are IIDs (even if they are not).
  
          :return: scaled exposure time