def addSetZoneCompleteCallback(self, callback, priority=None):
if self._setZoneCompleteCallbacks:
return self._setZoneCompleteCallbacks.add(callback, priority)
else:
token = PriorityCallbacks.GetToken()
fdc = SubframeCall(callback,
taskMgr.getCurrentTask().getPriority() - 1)
self._setZoneCompleteLocalCallbacks[token] = fdc
return token
