fier">wait_all_until_error_source</span><span class="special">()</span></code>. The caller must both retrieve a <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span>
          <span class="identifier">T</span> <span class="special">&gt;</span></code>
          and call its <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>
          method. It would, of course, be possible to return a fa&#231;ade over the cons