code: public function recordIsDeletedFromStage()
      {
          // for SiteTree records
          if ($this->owner->hasMethod('getIsDeletedFromStage')) {
              return $this->owner->IsDeletedFromStage;
          }
  
          if (!$this->owner->record->checkVersioned()) {
              return false;
          }
  
          if (!$this->owner->record->isInDB()) {
              return true;
          }
  
          $class = $this->owner->record->class;
  
          $stageVersion = Versioned::get_versionnumber_by_stage($class, 'Stage', $this->owner->record->ID);
  
          // Return true for both completely deleted pages and for pages just deleted from stage
          return !($stageVersion);
      }
docs: Determines if the current record is deleted from stage
  @return boolean