span><span class="ot">NULL</span>]</span>
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true"></a><span class="kw">head</span>(flights)</span>
<span id="cb11-3"><a href="#cb11-3" aria-hidden="true"></a><span class="co">#    year month day dep_delay arr_delay carrier origin dest air_time distance hour    speed</span></span>
<span id="cb11-4"><a href="#cb11-4" aria-hidden="true"></a><span class="co"># 1: 2014     1   1        14        13      AA    JFK  LAX      359     2475    9 413.6490</span></span>
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