$pagePicker->modelForQuery()
Returns a model object for the given query, depending on the parent and subpages options.
$pagePicker->modelForQuery(): Kirby\Cms\Page|Kirby\Cms\Site|nullReturn types
Kirby\Cms\PageorKirby\Cms\Siteornull
This method modifies the existing $pagepicker object it is applied to and returns it again.