Python RuntimeError: thread.__init__() not called解决方法

在写一个多线程类的时候调用报错
RuntimeError: thread.__init__() not called

代码如下:

class NotifyTread(threading.Thread): 
    def __init__(self, params): 
        threading.Thread.__init__(self)  #here。。。。。。 
        self.params = params 
     
    def run(self): 
        print "start notify............" 
        time.sleep(10) 
        print notify_tran(self.params) 
        print "end notify.............."