on</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.extension<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pcty_open</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.open_description&nbsp;*&nbsp;<span class="constructor">Parsetree</span>.class_type<br>
&nbsp;&nbsp;<span class="keyword">and</span>&nbsp;class_signature&nbsp;=&nbsp;{<br>
&nbsp;&nbsp;&nbsp;&nbsp;pcsig_self&nbsp;