Method fail

python-package/compile/src/io/json11.cpp:361–363

fail(msg, err_ret = Json()) * * Mark this parse as failed. */

     * Mark this parse as failed.
     */
    Json fail(string &&msg) {
        return fail(move(msg), Json());
    }

    template <typename T>
    T fail(string &&msg, const T err_ret) {