special>(                   </span><span class=comment>// inner subrule group, scope of b and c
            </span><span class=identifier>c </span><span class=special>= </span><span class=identifier>ch_p</span><span class=special>(</span><span class=literal>'c'</span><span class=special>),
            </span><span class=identifier>d </span><span class=special>= </span><span class=identifier>ch_p</span><span class=special>(</span><span class=literal>'d'</span><span class=special>)
        </span><span class=