 class="op">(</span><span class="st">"Coal"</span>, <span class="st">"Solar"</span><span class="op">)</span><span class="op">)</span><span class="op">)</span></span>
<span><span class="co">#&gt;             Motors -&gt; MD Cars -&gt; MD LED lamps -&gt; Light</span></span>
<span><span class="co">#&gt; All sources            5          7                  9</span></span>
<span></span>
<span><span class="fu"><a href="../reference/aggregate_pieces_byname.html">aggregate_pieces_byname</a></span><span class="op">(