_byname</a></span><span class="op">(</span><span class="va">m</span>, aggregation_map <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/list.html" class="external-link">list</a></span><span class="op">(</span>guitarists <span class="op">=</span> <span class="st">"^[JPG]"</span><span class="op">)</span>, </span>
<span>                 margin <span class="op">=</span> <span class="fl">2</span>, pattern_type <span class="op">=</span> <span class="st">"literal"</span><span class="op">)<