async_write</span><span class="special">(</span><span class="identifier">stream</span><span class="special">,</span> <span class="identifier">req</span><span class="special">,</span> <span class="identifier">yield</span><span class="special">[</span><span class="identifier">ec</span><span class="special">]);</span>
            <span class="keyword">if</span><span class="special">(</span><span class="identifier">ec</span><span class="special">)</span>
                <span class="keyword">return</span><span 