   <span class="special">{</span>
        <span class="identifier">add</span>
            <span class="special">(</span><span class="string">"X"</span>    <span class="special">,</span> <span class="number">10</span><span class="special">)</span>
            <span class="special">(</span><span class="string">"XX"</span>   <span class="special">,</span> <span class="number">20</span><span class="special">)</span>
            <span class="special">(</span><span class="string">"XXX"</span>  <span class="specia