code: def _add_watch_block(self, params, filterCb, capacity=500, cb=None):
  		
  		if (self._wbslock == None):
  			self._wbslock = Lock()
  
  		self._wbslock.acquire()
  		wb = WatchBlock(params, filterCb, capacity, cb)  # Add a List of Watchers
  		if ((wb != None) and (wb.cb == None)):
  			wb.cb = wb._dequeue_default_cb
  
  		self._wbs.append(wb)
  		self._wbslock.release()
  
  		if self._cookie == None:
  			return None
  		if wb != None and len(self._wbs) == 1 and wb.params["pollSec"] == None:
  			self._start_enqueue_thread()
  		if self._enqueueThread == None:
  			return wb
  
  		self._enqueueThreadSignal.acquire()
  		self._enqueueThreadSignal.notify()  # Notify
  		self._enqueueThreadSignal.release()  # Release the Lock
  
  		return wb
docs: Internal method to add a watch block for starting event monitoring.