code: def start(self, exit=True):
          
          on_start = self()
          actor = arbiter()
          if actor and on_start:
              actor.start(exit=exit)
              if actor.exit_code is not None:
                  return actor.exit_code
          return on_start
docs: Invoked the application callable method and start
          the ``arbiter`` if it wasn't already started.
  
          It returns a :class:`~asyncio.Future` called back once the
          application/applications are running. It returns ``None`` if
          called more than once.