nplay"></a><h3 class="anchor"><code><span class="label label-meta label-meta-optional" title="Marks the field of a structure as optional.">@:optional</span><span class="label label-optional">optional</span><a href="#onplay"><span class="identifier">onplay</span></a>:<a class="type" title="Null - Null&amp;lt;T&amp;gt; is a wrapper that can be used to make the basic types Int, Float and Bool nullable on static targets." href="../../../Null.html">Null</a>&lt;<a class="type" title="haxe.Function - This type uni