ode> object must follow the same restrictions as enforced by
<a href="dart-isolate/SendPort/send.html">SendPort.send</a>.
It is recommended to only use simple values that can be sent to all
isolates, like <code>null</code>, booleans, numbers or strings.</p>
<p>If the isolate is alive, it will eventually send <code>response</code>
(defaulting to <code>null</code>) on the response port.</p>
<p>The <code>priority</code> must be one of <a href="dart-isolate/Isolate/immediate-constant.html">immediate</a> or <a h