rite_substring&nbsp;:<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">UnixLabels</span>.file_descr&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;buf:string&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;pos:int&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;len:int&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;int<br>
&nbsp;&nbsp;<span class="keyword">val</span>&nbsp;single_write_substring&nbsp;:<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">UnixLabels</span>.file_descr&nbsp;<span cl