meterized callback for subsequent use. This parameter defaults to an empty array.</p><p></p></td></tr></table></div><p>This hook is useful, for example, when creating an event handler that will move the checkpoint. In this case, the parameter will likely be the event, so that you can use data from it as the checkpoint <a href="/api/common/type-aliases/identity/id/"><code>Id</code></a> to move to.</p><p>The optional first parameter is a function which will produce the label that will then be used to name the