 class="op">(</span>sum <span class="op">=</span> <span class="va">dep_delay</span> <span class="op">+</span> <span class="va">arr_delay</span><span class="op">)</span></span>
<span>           <span class="op">)</span></span></code></pre></div>
<p>However, I don’t recommend using it if you don’t acutually need it
for group computation (just start another pipe follows
<code>group_dt</code>). Now let’s end with some easy examples:</p>
<div class="sourceCode" id="cb27"><pre class="downlit sourceCode r">
