@Override protected AutoBuffer writeAll_impl(AutoBuffer ab) {
    ab.putKey(_output._u_key);
    ab.putKey(_output._v_key);
    return super.writeAll_impl(ab);
  }
@ Override protected AutoBuffer writeAll_impl ( AutoBuffer ab ) { ab . putKey ( _output . _u_key ) ; ab . putKey ( _output . _v_key ) ; return super . writeAll_impl ( ab ) ; }
Write out K/V pairs