r&lt;City, std::string, &amp;City::name&gt; type;
};

} }
</pre>
<p>That's it! One can now refer to vertices by name when interacting with
the distributed adjacency list.</p>
<p>What happens when one uses the name of a vertex that does not exist?
For example, in our <tt class="docutils literal"><span class="pre">add_edge</span></tt> call above, what happens if the
vertex named &quot;Indianapolis&quot; has not yet been added to the graph? By
default, the distributed adjacency list will throw an exception if 