<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def stop_traffic(self, *ports):
 """ Stop traffic on list of ports. :param ports: list of ports to stop traffic on. Default - all session ports. """


        for chassis, chassis_ports in self._per_chassis_ports(*self._get_operation_ports(*ports)).items():
            chassis.stop_traffic(*chassis_ports)