def adj_par_names(self):
        """ wrapper around pyemu.Pst.adj_par_names for list adjustable parameter
        names

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

        Returns
        -------
        adj_par_names : list
            pyemu.Pst.adj_par_names