sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">Parsetree</span>.expression<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pexp_letexception</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.extension_constructor&nbsp;*<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="constructor">Parsetree</span>.expression<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span 