/**
  * Go throught tree upward to find all parents
  */
 private static function getParents(SiteTree $page)
 {
     $parents = array();
     $parent = $page->parent();
     while ($parent && $parent->exists()) {
         array_push($parents, $parent);
         // Keep looping
         $parent = $parent->parent();
     }
     return $parents;
 }