le_descr&nbsp;list<br>
&nbsp;&nbsp;<span class="keyword">type</span>&nbsp;lock_command&nbsp;=<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">Unix</span>.lock_command&nbsp;=<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">F_ULOCK</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">F_LOCK</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">F_TLOCK</span><br>
&nbsp;&nbsp;&nbsp;&nbsp;<span 