class myClass(object):
    watcher = None

    @staticmethod
    def launch():
        th = Thread(target = myClass.watcherThread, name = "myClass watcher thread")
        th.daemon = True
        th.start()
        myClass.watcher = th

    @staticmethod
    def stop():
        myClass.watcher = None

    @staticmethod
    def watcherThread():
        while(true):

            #some code

            if(myClass.watcher == None):
                break