   peer on an established connection, and can appear in between continuation
        frames for a message. There are three types of control frames: ping, pong,
        and close.
      </p>
<p>
        A sent ping indicates a request that the sender wants to receive a pong.
        A pong is a response to a ping. Pongs may be sent unsolicited, at any time.
        One use for an unsolicited pong is to inform the remote peer that the session
        is still active after a long period of inactivity. A close 