code: def _get_interface_name_from_hosting_port(self, port):
          
          try:
              vlan = port['hosting_info']['segmentation_id']
              int_prefix = port['hosting_info']['physical_interface']
              return '%s.%s' % (int_prefix, vlan)
          except KeyError as e:
              params = {'key': e}
              raise cfg_exc.DriverExpectedKeyNotSetException(**params)
docs: Extract the underlying subinterface name for a port
          e.g. Port-channel10.200 or GigabitEthernet0/0/0.500