">=</span> <span class="st">"calculated"</span>,</span>
<span class="r-in">     formula <span class="op">=</span> <span class="st">"second_column * 2"</span></span>
<span class="r-in">   <span class="op">)</span></span>
<span class="r-in"> <span class="op">)</span></span>
<span class="r-in"><span class="op">)</span></span>
<span class="r-in"></span>
<span class="r-in"><span class="fu">random_data_frame</span><span class="op">(</span><span class="va">conf</span>, size <span class="op">=</span> <span class="f