title: How can I get the data inside a beast::flat_buffer?
body: <p>I'm connecting to a websocket using the boost/beast libraries and writing the data into a <code>beast::flat_buffer</code>. My issue is that I'm having trouble getting the data from <code>buffer</code>. I have a thread-safe <code>channel</code> object that I can to write to, but I'm not sure how to pull the most recently received message from the <code>buffer</code>.</p>
  <pre class="lang-cpp prettyprint-override"><code>beast::flat_buffer buffer;
  // send through socket
  send_socket(
     ws, get_subscribe_string(trade_tickers, bar_tickers, quote_tickers));
  // read into buffer
  while (channel.running) {
     ws.read(buffer); // need to write the most recently received message into the channel
  }
  </code></pre>
  <p>I can write to the channel with <code>channel.write(std::string arg)</code>. Any ideas on how to pull from the <code>buffer</code>?</p>