     ...</span>
<span id="cb5-4"><a href="#cb5-4" aria-hidden="true"></a>)]</span></code></pre></div></li>
</ol>
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<h4 class="bs-callout bs-callout-warning"></h4>
<p>Note that the code above explains how <code>:=</code> can be used. They are not working examples. We will start using them on <code>flights</code> <em>data.table</em> from the next section.</p>
</div>
</div>
</div>
<div id="section-2" class="section level1">
<h1></h1>
<div 