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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 unregister_switch_address(addr):
 """ Unregister the given switch address. Unregisters the given switch address to let ryu.controller.controller.OpenFlowController stop trying to initiate connection to switch. :param addr: A tuple of (host, port) pair of switch. """

    ofp_handler = app_manager.lookup_service_brick(ofp_event.NAME)
    # Do nothing if ofp_handler is not started yet
    if ofp_handler.controller is None:
        return
    ofp_handler.controller.stop_client_loop(addr)