<span class="op">&lt;-</span> <span class="va">LETTERS</span><span class="op">[</span><span class="fl">1</span><span class="op">:</span><span class="fl">9</span><span class="op">]</span>;</span></span>
<span class="r-in"><span><span class="va">use_groups</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/rep.html" class="external-link">rep</a></span><span class="op">(</span><span class="va">letters</span><span class="op">[</span><span class="fl">1</span><span class="op">:<