an>.file_descr&nbsp;list&nbsp;<span class="keywordsign">-&gt;</span>
&nbsp;&nbsp;&nbsp;&nbsp;float&nbsp;<span class="keywordsign">-&gt;</span>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">Unix</span>.file_descr&nbsp;list&nbsp;*&nbsp;<span class="constructor">Unix</span>.file_descr&nbsp;list&nbsp;*&nbsp;<span class="constructor">Unix</span>.file_descr&nbsp;list
&nbsp;&nbsp;<span class="keyword">val</span>&nbsp;pipe&nbsp;:&nbsp;unit&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="constructo