ttps://rdrr.io/r/utils/install.packages.html" class="external-link">install.packages</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="st">"devtools"</span>, <span class="st">"roxygen2"</span>, <span class="st">"testthat"</span>, <span class="st">"knitr"</span>, <span class="st">"rmarkdown"</span><span class="op">)</span><span class="op">)</span></span>
<span></span>
<span><span class="co"># Ins