How to use the pyodesys.util._Callback function in pyodesys

def get_jtimes_callback(self):
        """ Generate a callback fro evaluating the jacobian-vector product."""
        jtimes = self.get_jtimes()
        if jtimes is False:
            return None
        v, jtimes_exprs = jtimes
        return _Callback(self.indep, tuple(self.dep) + tuple(v), self.params,
                         jtimes_exprs, Lambdify=self.be.Lambdify)

def _get_analytic_callback(ori_sys, analytic_exprs, new_dep, new_params):
        return _Callback(ori_sys.indep, new_dep, new_params, analytic_exprs, Lambdify=ori_sys.be.Lambdify)

def _callback_factory(self, exprs):
        return _Callback(self.indep, self.dep, self.params, exprs, Lambdify=self.be.Lambdify)

new_latex_par_names : iterable of str
            TeX formatted names of the new parameters given in ``new_pars``.
        \\*\\*kwargs:
            Keyword arguments passed to ``.from_other``.

        Returns
        -------
        Intance of the class
        extra : dict with keys:
            - recalc_params : ``f(t, y, p1) -> p0``

        """
        new_exprs = [expr.subs(par_subs) for expr in ori.exprs]
        drop_idxs = [ori.params.index(par) for par in par_subs]
        params = _skip(drop_idxs, ori.params, False) + list(new_pars)
        back_substitute = _Callback(ori.indep, ori.dep, params, list(par_subs.values()),
                                    Lambdify=ori.be.Lambdify)

        def recalc_params(t, y, p):
            rev = back_substitute(t, y, p)
            return _reinsert(drop_idxs, np.repeat(np.atleast_2d(p), rev.shape[0], axis=0),
                             rev)[..., :len(ori.params)]

        return cls.from_other(
            ori, dep_exprs=zip(ori.dep, new_exprs),
            params=params,
            param_names=_skip(drop_idxs, ori.param_names, False) + list(new_par_names or []),
            latex_param_names=_skip(drop_idxs, ori.latex_param_names, False) + list(new_latex_par_names or []),
            **kwargs
        ), {'recalc_params': recalc_params}