code: def start(self, user_func, refresh):
  		
  		self.update=user_func
  		self.refresh=refresh
  		self.error=None
  
  		# First load
  		self.update()
  		self.commit()
  
  		# Start updater thread
  		up = threading.Thread(None,self.main_update,"Updater")
  		up.daemon = True
  		up.start()
  
  		# Main loop
  		while up.isAlive(): # Do not serve data if the Updater thread has died
  			try:
  				self.main_passpersist()
  			except:
  				up._Thread__stop()
  				raise
docs: Start the SNMP's protocol handler and the updater thread
  		user_func is a reference to an update function, ran every 'refresh' seconds.