>origin</span>, <span class="va">dest</span>, <span class="va">month</span><span class="op">)</span>,</span>
<span>    <span class="fu">at_dt</span><span class="op">(</span><span class="st">"_delay"</span>,<span class="va">summarise_dt</span>,<span class="va">mean</span><span class="op">)</span> <span class="op"><a href="https://magrittr.tidyverse.org/reference/pipe.html" class="external-link">%&gt;%</a></span> </span>
<span>      <span class="fu"><a href="../reference/mutate.html">mutate_dt</a></span><span