code: def lbnd(self):
          
          if not self.istransformed:
              return self.pst.parameter_data.parlbnd.copy()
          else:
              lb = self.pst.parameter_data.parlbnd.copy()
              lb[self.log_indexer] = np.log10(lb[self.log_indexer])
              return lb
docs: the lower bound vector while respecting log transform
  
          Returns
          -------
          lbnd : pandas.Series