tor&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="constructor">Parsetree</span>.type_declaration&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;unit;<br>
&nbsp;&nbsp;&nbsp;&nbsp;type_extension&nbsp;:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">Ast_iterator</span>.iterator&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="constructor">Parsetree</span>.type_extension&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;unit;<br>
&nbsp;&nbsp;&nbsp;&nbsp;type_exce