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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 add(self, interface_id, virtual_mapping=None, virtual_resource_name=None, zone_ref=None, comment=None):
 """ Add single physical interface with interface_id. Use other methods to fully add an interface configuration based on engine type. Virtual mapping and resource are only used in Virtual Engines. :param str,int interface_id: interface identifier :param int virtual_mapping: virtual firewall id mapping See :class:`smc.core.engine.VirtualResource.vfw_id` :param str virtual_resource_name: virtual resource name See :class:`smc.core.engine.VirtualResource.name` :raises EngineCommandFailed: failure creating interface :return: None """

        interface = Layer3PhysicalInterface(engine=self._engine,
            interface_id=interface_id, zone_ref=zone_ref,
            comment=comment, virtual_resource_name=virtual_resource_name,
            virtual_mapping=virtual_mapping)
        
        return self._engine.add_interface(interface)