> <span class="fu"><a href="https://rdrr.io/r/base/sum.html" class="external-link">sum</a></span><span class="op">(</span><span class="va">flights</span><span class="op">)</span><span class="op">)</span></span>
<span></span>
<span><span class="co"># (per_year  &lt;- summarise(per_month, flights = sum(flights)))</span></span>
<span><span class="va">flights</span> <span class="op"><a href="https://magrittr.tidyverse.org/reference/pipe.html" class="external-link">%&gt;%</a></span> </span>
<span>  <span class="