cond overload must be used when the
graph doesn't have an internal vertex index map, which must then be
supplied with the appropriate parameter.</p>
<div class="contents topic" id="contents">
<p class="topic-title first">Contents</p>
<ul class="simple">
<li><a class="reference internal" href="#where-defined" id="id2">Where Defined</a></li>
<li><a class="reference internal" href="#parameters" id="id3">Parameters</a></li>
<li><a class="reference internal" href="#example" id="id4">Example</a></li>
<li><a class