dentifier">host_rank</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  <span class="keyword">static</span> <span class="identifier">optional</span><span class="special">&lt;</span> <span class="keyword">int</span> <span class="special">&gt;</span> <a class="link" href="environment.html#idp43962464-bb"><span class="identifier">io_rank</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  <span class="keyword