o be notified of control
        frames, callers may register a <span class="emphasis"><em>control callback</em></span> using
        <a class="link" href="../ref/boost__beast__websocket__stream/control_callback.html" title="websocket::stream::control_callback"><code class="computeroutput"><span class="identifier">control_callback</span></code></a>. The object provided
        with this option should be callable with the following signature:
      </p>
<pre class="programlisting"><span class="identifier">ws