code: def detx(self, det_id, t0set=None, calibration=None):
          
          url = 'detx/{0}?'.format(det_id)    # '?' since it's ignored if no args
          if t0set is not None:
              url += '&t0set=' + t0set
          if calibration is not None:
              url += '&calibrid=' + calibration
  
          detx = self._get_content(url)
          return detx
docs: Retrieve the detector file for given detector id
  
          If t0set is given, append the calibration data.