lass="special">-&gt;</span><span class="identifier">close</span><span class="special">();</span>
            <span class="comment">// show caller the value we got</span>
            <span class="keyword">return</span> <span class="identifier">future</span><span class="special">.</span><span class="identifier">get</span><span class="special">();</span>
        <span class="special">}</span>

        <span class="comment">// error is non-null: collect</span>
        <span class="identifier">exceptions</span><