 callback</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>

<dl class="method">
<dt>
<tt class="descname">Clear</tt><big>(</big><span class="optional">[</span><em>callback</em><span class="optional">]</span><big>)</big></dt>
<dd><p>This causes the history of past messages to be cleared so new
listeners will not receive them.  Note that since the signal may
be operating asynchronously, the <a class="reference internal" href="message.html#Clear" title="Clear"><tt class="xref py py-meth docutils literal"><span cla