xpression&nbsp;option<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pexp_sequence</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.expression&nbsp;*&nbsp;<span class="constructor">Parsetree</span>.expression<br>
&nbsp;&nbsp;&nbsp;&nbsp;<span class="keywordsign">|</span>&nbsp;<span class="constructor">Pexp_while</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">Parsetree</span>.expression&nbsp;