tes: <em>transient</em> or <em>long-running</em>.
 </p>

 <ul>
 <li>By default, a conversation is transient</li>
 <li>A transient conversation may be marked long-running by calling <a href="Conversation.html#begin()"><code>Conversation.begin()</code></a></li>
 <li>A long-running conversation may be marked transient by calling <a href="Conversation.html#end()"><code>Conversation.end()</code></a></li>
 </ul>

 <p>
 All long-running conversations have a string-valued unique identifier, which may be set by the 