code: def register_halfmaxes(self, telescope, band, lower, upper):
          
  
          if (telescope, band) in self._halfmaxes:
              raise AlreadyDefinedError('half-max points for %s/%s already '
                                        'defined', telescope, band)
          self._note(telescope, band)
          self._halfmaxes[telescope,band] = (lower, upper)
          return self
docs: Register precomputed half-max points.