an class="cn">NULL</span>,</span>
<span>  .sort <span class="op">=</span> <span class="cn">TRUE</span>,</span>
<span>  .groups <span class="op">=</span> <span class="st">"drop_last"</span>,</span>
<span>  .unpack <span class="op">=</span> <span class="cn">FALSE</span></span>
<span><span class="op">)</span></span>
<span></span>
<span><span class="fu">summarise</span><span class="op">(</span></span>
<span>  <span class="va">.df</span>,</span>
<span>  <span class="va">...</span>,</span>
<span>  .by <span class