public static void unregister(SPINThreadFunctions old){
  if (old != null) {
    localFunctions.set(old);
  }
 else {
    localFunctions.remove();
  }
}

public static void unregister ( SPINThreadFunctions old ) { if ( old != null ) { localFunctions . set ( old ) ; } else { localFunctions . remove ( ) ; } }
unregisters the current model for the current thread .
