s="fu">group</span><span class="op">(</span><span class="st">'['</span>, <span class="fu"><a href="https://rdrr.io/r/base/list.html" class="external-link">list</a></span><span class="op">(</span><span class="va">i</span>, <span class="va">j</span><span class="op">)</span>, <span class="st">']'</span><span class="op">)</span><span class="op">]</span>,</span></span>
<span class="r-in"><span>                       <span class="fu"><a href="https://rdrr.io/r/base/list.html" class="external-link">list</a></span>