etree</span>.class_expr<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pcl_constraint</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.class_expr&nbsp;*&nbsp;<span class="constructor">Parsetree</span>.class_type<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pcl_extension</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.extension<