/index.html#type-boxkind">Expression.boxkind</a> <span class="arrow">&#45;&gt;</span></span>
  <span><a href="Expression/index.html#type-t">Expression.t</a> <span class="arrow">&#45;&gt;</span></span>
  <span>of_:<a href="Expression/index.html#type-t">Expression.t</a> <span class="arrow">&#45;&gt;</span></span>
  <span><a href="Expression/index.html#type-t">Expression.t</a> <span class="xref-unresolved">Base</span>.option</span></span></code></div></div><div class="odoc-spec"><div class="spec value" id="val