           of the handler must be:
</p>
<pre class="programlisting">void handler(
  const boost::system::error_code&amp; error // Result of operation
);
</pre>
<p>
                Regardless of whether the asynchronous operation completes immediately
                or not, the handler will not be invoked from within this function.
                Invocation of the handler will be performed in a manner equivalent
                to using <code class="computeroutput">boost::asio::io_context::post()</code>.
 