reference internal" href="message.html#Clear" title="Clear"><tt class="xref py py-meth docutils literal"><span class="pre">Clear()</span></tt></a>
operation is completed.</p>
<p>Returns the callback (or a blank callback if none is provided).</p>
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<tr class="field"><th class="field-name">Parameters :</th><td class="field-body"><ul class="first simple">
<li><strong>callback</