n><span class="op">~</span><span class="va">B</span><span class="op">+</span><span class="va">C</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-plt img"><img src="DAG-2.png" alt="" width="700" height="433"></span>
<span class="r-in"><span>  <span class="co"># Add a node as it's own parent to create an isolate:</span></span></span>
<span class="r-in"><span>  <span class="fu"><a href="https://rdrr.io/r/graphics/plot.default.html" class="external-link">plot</a></span><span