erface.AbstractValue.t</a> * <a href="../PulseValueHistory/index.html#type-t">PulseBasicInterface.ValueHistory.t</a></code></dt><dt class="spec type" id="type-t"><a href="#type-t" class="anchor"></a><code><span class="keyword">type</span> t</code></dt></dl><dl><dt class="spec value" id="val-empty"><a href="#val-empty" class="anchor"></a><code><span class="keyword">val</span> empty : <a href="index.html#type-t">t</a></code></dt><dt class="spec value" id="val-is_empty"><a href="#val-is_empty" class="anchor"><