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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:
 async def close(self):
 """ Terminate the ICE agent, ending ICE processing and streams. """

        if self.__isClosed:
            return
        self.__isClosed = True
        self.__setSignalingState('closed')

        # stop senders / receivers
        for transceiver in self.__transceivers:
            await transceiver.stop()
        if self.__sctp:
            await self.__sctp.stop()

        # stop transports
        for transceiver in self.__transceivers:
            await transceiver._transport.stop()
            await transceiver._transport.transport.stop()
        if self.__sctp:
            await self.__sctp.transport.stop()
            await self.__sctp.transport.transport.stop()
        self.__updateIceConnectionState()

        # no more events will be emitted, so remove all event listeners
        # to facilitate garbage collection.
        self.remove_all_listeners()