9"><a href="#cb15-9" aria-hidden="true"></a><span class="co"># 5: 2014     1   1         2         1      AA    JFK  LAX      350     2475   13</span></span>
<span id="cb15-10"><a href="#cb15-10" aria-hidden="true"></a><span class="co"># 6: 2014     1   1         4         0      AA    EWR  LAX      339     2454   18</span></span></code></pre></div>
<div id="and-copy" class="section level2">
<h2>3) <code>:=</code> and <code>copy()</code></h2>
<p><code>:=</code> modifies the input object by reference. Apart 