ass="op">(</span><span class="va">e1</span>, e2 <span class="op">=</span> <span class="cn">NULL</span><span class="op">)</span>

<span class="co"># S3 method for mesh3d</span>
<span class="fu"><a href="https://rdrr.io/r/base/groupGeneric.html" class="external-link">Ops</a></span><span class="op">(</span><span class="va">e1</span>, e2 <span class="op">=</span> <span class="cn">NULL</span><span class="op">)</span>

<span class="co"># S3 method for hxsurf</span>
<span class="fu"><a href="https://rdrr.io/r/base