/**
  * Short description of method singleton
  *
  * @access public
  * @author Jerome Bogaerts, <*****@*****.**>
  * @return core_kernel_classes_Resource
  */
 public static function singleton()
 {
     $returnValue = null;
     if (core_kernel_persistence_smoothsql_Property::$instance == null) {
         core_kernel_persistence_smoothsql_Property::$instance = new core_kernel_persistence_smoothsql_Property();
     }
     $returnValue = core_kernel_persistence_smoothsql_Property::$instance;
     return $returnValue;
 }