urce <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">"latest"</span>, <span class="st">"local"</span>, <span class="st">"custom"</span><span class="op">)</span>,</span>
<span>  custom_uri <span class="op">=</span> <span class="cn">NULL</span>,</span>
<span>  use_local_fallback <span class="op">=</span> <span class="cn">TRUE</span></span>
<span><span class="op">)</span></span></code></pre></div>
