tifier">offset_</span><span class="special">;</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">total_bytes_transferred_</span><span class="special">;</span>

  <span class="comment">// Function call operator meeting WriteHandler requirements.</span>
  <span class="comment">// Used as the handler for the async_write_some operation.</span>
  <span class="keyword">void</span> <span class="keyword">operator</span><span cla