e type of frame and payload text are passed
        as parameters to the control callback. If the frame is a close frame, the
        close reason may be obtained by calling <a class="link" href="../ref/boost__beast__websocket__stream/reason.html" title="websocket::stream::reason"><code class="computeroutput"><span class="identifier">reason</span></code></a>.
      </p>
<p>
        Unlike regular completion handlers used in calls to asynchronous initiation
        functions, the control callback only needs 