span class="op">(</span><span class="fl">1</span><span class="op">:</span><span class="fl">9</span>, nrow<span class="op">=</span><span class="fl">3</span><span class="op">)</span>, <span class="st">"matrix"</span><span class="op">)</span>   <span class="co"># TRUE</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> [1] TRUE</span>
<span class="r-in"><span>  <span class="fu">check_type</span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/data.frame.html" 