span><span class="special">::</span><span class="identifier">async_write</span></code></a>, or <a class="link" href="async_write_some.html" title="websocket::stream::async_write_some"><code class="computeroutput"><span class="identifier">websocket</span><span class="special">::</span><span class="identifier">stream</span><span class="special">::</span><span class="identifier">async_write_some</span></code></a> are performed
          until this operation completes. If this is the beginning of a new message,