code: def adj_par_names(self):
          
          if self.__pst is not None:
              return self.pst.adj_par_names
          else:
              return self.jco.par_names
docs: wrapper around pyemu.Pst.adj_par_names for list adjustable parameter
          names
  
          Returns
          -------
          adj_par_names : list
              pyemu.Pst.adj_par_names