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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 cancel_port_forward(self, address, port):
 """ Ask the server to cancel a previous port-forwarding request. No more connections to the given address & port will be forwarded across this ssh connection. :param str address: the address to stop forwarding :param int port: the port to stop forwarding """

        if not self.active:
            return
        self._tcp_handler = None
        self.global_request("cancel-tcpip-forward", (address, port), wait=True)