an><span class="op">(</span><span class="st">"g"</span>,<span class="st">"p"</span>,<span class="st">"r"</span><span class="op">)</span>,</span></span>
<span class="r-in"><span>       index <span class="op">=</span> <span class="kw">function</span><span class="op">(</span><span class="va">x</span>,<span class="va">y</span><span class="op">)</span> <span class="fu"><a href="https://rdrr.io/r/stats/coef.html" class="external-link">coef</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.