
<a class="sourceLine" id="cb4-8" data-line-number="8">p &lt;-<span class="st"> </span></a>
<a class="sourceLine" id="cb4-9" data-line-number="9"><span class="st">  </span><span class="kw"><a href="https://ggplot2.tidyverse.org/reference/ggplot.html">ggplot</a></span>(sleep) <span class="op">+</span></a>
<a class="sourceLine" id="cb4-10" data-line-number="10"><span class="st">  </span><span class="kw"><a href="https://ggplot2.tidyverse.org/reference/aes.html">aes</a></span>(group, extra) <span class="op">+<