ssociated with the handler through the use of
                    argument dependent lookup overloads of functions such as <code class="computeroutput"><span class="identifier">asio_handler_allocate</span></code>.
                  </p>
<p>
                    The Beast completion handler is provided at the call site. For
                    each call to an asynchronous initiation function, it is guaranteed
                    that there will be exactly one final call to the handler. This
                  