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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_subscriber(self, subscriber, precedence=0):
 """ Register a callable subscriber to this stream which will be invoked either when event is called or when this stream is passed to the trigger classmethod. Precedence allows the subscriber ordering to be controlled. Users should only add subscribers with precedence between zero and one while HoloViews itself reserves the use of higher precedence values. Subscribers with high precedence are invoked later than ones with low precedence. """

        if not callable(subscriber):
            raise TypeError('Subscriber must be a callable.')
        self._subscribers.append((precedence, subscriber))