n><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span>   <span class="comment">// Number of bytes written from the</span>
                                    <span class="comment">// buffers. If an error occurred,</span>
                                    <span class="comment">// this will be less than the sum</span>
                                    <span class="comment">// of the buffer sizes.</span>
<span class="special">);</span>
</pr