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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 close(self, reason=None, within=0):
 """Explicitely close the connection. @param reason: Optional closing reason. If not given, ConnectionDone will be used. @param within: Shutdown the client within this amount of seconds. If zero (the default), all channels and queues will be closed immediately. If greater than 0, try to close the AMQP connection cleanly, by sending a "close" method and waiting for "close-ok". If no reply is received within the given amount of seconds, the transport will be forcely shutdown. """

        if self.closed:
            return

        if reason is None:
            reason = ConnectionDone()

        if within > 0:
            channel0 = yield self.channel(0)
            deferred = channel0.connection_close()
            call = self.clock.callLater(within, deferred.cancel)
            try:
                yield deferred
            except defer.CancelledError:
                pass
            else:
                call.cancel()

        self.do_close(reason)