function appliesTo($class, $includeSubclasses)
 {
     // Include all DataExtensions that contain a SubsiteID.
     // TODO: refactor subsites to inherit a common interface, so we can run introspection once only.
     return SearchIntrospection::has_extension($class, 'SiteTreeSubsites', $includeSubclasses) || SearchIntrospection::has_extension($class, 'GroupSubsites', $includeSubclasses) || SearchIntrospection::has_extension($class, 'FileSubsites', $includeSubclasses) || SearchIntrospection::has_extension($class, 'SiteConfigSubsites', $includeSubclasses);
 }
 function appliesTo($class, $includeSubclasses)
 {
     return SearchIntrospection::has_extension($class, 'SiteTreeSubsitesPolyhome', $includeSubclasses);
 }
 function appliesTo($class, $includeSubclasses)
 {
     return SearchIntrospection::has_extension($class, 'Versioned', $includeSubclasses);
 }