code: def _load_nexus_cfg_driver(self):
          
  
          try:
              loaded_class = runtime_utils.load_class_by_alias_or_classname(
                  'networking_cisco.ml2.nexus_driver', 'restapi')
              return loaded_class(CONF.ml2_cisco.nexus_switches)
          except ImportError:
              LOG.error("Error loading Nexus Config driver 'restapi'")
              raise SystemExit(1)
docs: Load Nexus Config driver.
          :raises SystemExit of 1 if driver cannot be loaded