code: def execute(args):
      
      task_family = None
      error = None
  
      # try to infer the task module from the passed task family and import it
      parts = args.task_family.rsplit(".", 1)
      if len(parts) == 2:
          modid, cls_name = parts
          try:
              mod = __import__(modid, globals(), locals(), [cls_name])
              if hasattr(mod, cls_name):
                  task_cls = getattr(mod, cls_name)
                  if not issubclass(task_cls, Task):
                      abort("object '{}' is not a Task".format(args.task_family))
                  task_family = task_cls.task_family
          except ImportError as e:
              logger.warning("import error in module {}: {}".format(modid, e))
              error = e
  
      # read task info from the index file and import it
      if task_family is None:
          index_file = Config.instance().get_expanded("core", "index_file")
          if os.path.exists(index_file):
              info = read_task_from_index(args.task_family, index_file)
              if not info:
                  abort("task family '{}' not found in index".format(args.task_family))
              modid, task_family, _ = info
              __import__(modid, globals(), locals())
  
      # complain when no task could be found
      if task_family is None:
          if error:
              raise error
          else:
              abort("task '{}' not found".format(args.task_family))
  
      # import the module and run luigi
      luigi_run([task_family] + sys.argv[3:])
docs: Executes the *run* subprogram with parsed commandline *args*.