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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 _push_packet(self, packet):
 """ Appends a packet to the internal read queue, or notifies a waiting listener that a packet just came in. """

        self._read_queue.append((decode(packet), packet))

        if self._read_waiter is not None:
            w, self._read_waiter = self._read_waiter, None
            w.set_result(None)